[Inquisitor Octavian Lars]

I was going to say that you are cut off from your ship/all supplies are required.
Also, you may want to look poor

[Alyster Wick]

You could simplify things by having a random events table(s) that players roll on after each game.

At the kind of monetary scales Inquisitors/Rogue Traders/etc operate at, their income would easily stretch to supporting their water/ammo/etc requirements (unless someone's been blatting off heavy bolters full auto or something). [...]

As a question, how will you deal with characters who have their own warp capable craft? They carry months (if not years) of supplies and will have their own on-board armouries [...]
If push came to shove, few of my characters would have objections to shuttling down a couple of giant water drums and a big crate of ammo if they hit a real shortage of supplies...

I'm going to go ahead and agree with everything Kaled and Marco said. A table is a simple and elegant solution to your problem which also has the advantages of giving full excuses to some of the questions Marco raises (if a warp storm prevents any craft from landing it could be a big problem for everyone).

In the way of other solutions, you could perhaps have the planet be incredibly restricted with the access it gives to aircraft so the only way a warband could get resupplied without going through the normal routes would be by invoking their Inquisitorial privilege in which case their landing may attract the other warband to attempt to steal their supplies (not to mention other undesirables who, living on their backwater planet, do not full realize the power of the Inquisition).

Anyway, the store is great in concept but may be difficult in execution. Having a table to roll on will require the same careful ammo counting (as character will be completely unsure when they next supplies may come in) and difficult decisions without the extra hassle of screwing around tracking money. I can quickly see it becoming incredibly cumbersome and more of a chore versus the streamlines simplicity of a table. And as GM I think it will also help you come up with creative scenarios or at least give some added tension.

[MarcoSkoll]

How, exactly, are they cut off from the ship? If a shuttle got them down there to begin with, why can it not get food down? Players may get a bit bored of the "violent sandstorms" if they start just conveniently after their landing and they're now into what is apparently the third week of freak conditions.

Alyster Wick has something of an excuse, but I can see ways around that too.
Simply spreading around enough bribes would let you get around invoking Inquisitorial privelage - or if you were playing the part of the Inquisition, just simply refusing to tell anyone where you were going to land the shuttle (avoiding any pre-planted ambushes).
In either case, many characters would think little of bringing down a platoon of heavy armsmen with the shuttle to protect the delivery.

Also, what if their ship has a teleporter which can just get straight past such things? The "strong solar interference" line will also wear thin.

~~~~~

As far as resources being so stretched that a ship with thousands of crew seriously can't find enough resources to support its owner and his half dozen allies, what's to be said to simply finding a few of the menials and "firing them" (which could be between "you're no longer needed, get off the ship" to "No, this isn't one of the airlocks, what are you talking about...?") to make up that deficit?

Also, you may want to look poor

But that's a may.
Why would the characters want to look poor - are there going to be campaign advantages to pretending to be a dust worker rather than a wealthy noble?  If there aren't, then players will be keen to take on the wealthy cover identity that let them explain their equipment and resources... (particularly important when you've got to explain a character with expensive custom bionics).

Would all the characters even stoop to pretending to be lower class? I know I've got characters that wouldn't (or for reasons similar to the above bionic reasoning, couldn't).

[Inquisitor Octavian Lars]

Velterax is a militarised planet so maybe the air traffic control is tight, with slots booked weeks (read months) in advance, but I see what you mean about sandstorm/solar/lack of supplies excuses.

[Dolnikan]

You could perhaps have something like specific, regular windows which are the only time shuttles can fly, this could maybe be caused by solar radiation and only when a moon blocks this the shuttles can fly safely.

[Inquisitor Octavian Lars]

I felt my system shows the immense Beaurocracy of the imperium, but I could easily incorporate elements of your theory.

[Alyster Wick]

I felt my system shows the immense Beaurocracy of the imperium, but I could easily incorporate elements of your theory.

I think bureaucracy is a completely acceptable reason. Travel is extremely restricted to the major cities, it isn't impossible to travel outside of there but communications are heavily monitored. Inquisitorial code may be impossible to crack for most conventional Imperial agents but they can still tell when and where the communications occur (and maybe there is a talented savant unscrambling code for fun who stumbles upon something they were never supposed to hear).

Anyway, the Inquisitors clearly can get (well defended) supplies delivered but to do so would give away their status and take a good amount of time. If you have a campaign that necessitates secrecy (or at least strongly incentives it) and runs on a tight time table you're golden (even Inquisitors can't get around time, unless their ordos chronos I suppose...)

[Inquisitor Octavian Lars]

My plan was to have some stats such as rarity and finance
rarity represents how rare something is and to find it you subtract finance from Ld then take a test (multiple modifiers may be added and if passed, all items are found)
finance is a cost, so expensive items eat into your finance limit. This represents items like power and bolt weapons. Each group will have a finance limit decided in a characterful way.

[Draco Ferox]

Of course, as soon as my inquisitor's cover is blown, he's going to whip out his rosette and start requisitioning things like guns and supplies left, right and centre, as there's no need for stealth, and be might as well use it if he needs/wants/temporarily likes something. It's abuse of power,but with an unlimited amount, he's not going to run out any time soon.

Bureaucracy seems a good way to stop players doing things- they might well shuttle down more supplies in an unauthorised drop, but that could mean the non-cooperation of several of the main factions on the planet.

[Dolnikan]

If a character starts just requisitioning all sorts of things you could also give other players an edge against them, they are, after all, much easier to find.

[Ynek]

An easy way to add an advantage to "looking poor" is that people won't try to rob you.
If your Inquisitor, decked from head to toe in shiny things, happens to take a bullet to a tender spot during a firefight and gets knocked unconscious, a crowd of impoverished bystanders (read: thieves) might decide to descend upon the stricken hero and strip him of anything valuable.

That precious, thousand year old power sword and heirloom digi melta aren't worth much to you when they've been stolen, are they? That beaten up old revolver and flint knife sound pretty good about now, huh?

Also, I agree that the clerical system of a low-tech imperial world might mean that a person has to apply for landing clearance weeks in advance. Just because you are an Inquisitor with limitless authority does not mean that the planet's defences will KNOW that you are an inquisitor with limitless authority. After applying for landing clearance, the documents would have to be countersigned in triplicate and authenticated before being passed on to a reprographics officer who would in turn make several copies, each of which would be taken to the defensive batteries, where they would be examined by the commanding officer, and a read-reciept is sent back to general HQ, which is in turn countersigned in triplicate and filed in the proper and timely manner before the Inquisitor is told: "Yep. Safe for you to land now."

Just because you're an Inquisitor won't stop them from shooting you down if nobody has told them not to.

[Inquisitor Octavian Lars]

Good points there! I was planning to make an undercover version of octavian (like kaled)

[Draco Ferox]

Thanks for knocking down the requisitioning idea. I like it when people show me the weaknesses of what I am tying to achieve, so that I can do it better next time.

I like Ynek's description of the bureaucracy, but think that maybe a better description would be that of the Vogons in the hitchhiker's guide. To quote:

They wouldn't even lift a finger to save their own grandmothers from the Ravenous Bugblatter Beast of Traal without orders signed in triplicate, sent in, sent back, queried, lost, found, subjected to public inquiry, lost again, and finally buried in soft peat for three months and recycled as firelighters.

Sound like any self-important administratum adepts?