I'd say less 'buy' per say, as more create an incentive program for what we need.

Lets say, just like the give outs for Resurgent, we post up a 'wanted' list of X goods over X number of days with a yayout of Y per good every once in a while.

Example:
We need 80 (4 stacks) of Healing Food (cooked) or Fish (uncooked).
We'll pay 20g per stack of cooked food and 10g per stack of uncooked and half that after the amount is reached.

So that comes out to 1g per piece of food and 50s per fish donated of that particular item and then 50/25s after the quota has been met. Its true that you COULD sell it for possibly more on the AH, but its an incentive for making those gbank donations that are severly lacking.

Another idea, and one I'm quite in favor of, would be raid reward periods. If a raid is doing well or trying hard to learn a new boss then if the gbank was to be opened up for 3-4 minutes after the raid so that repairs could be made with guild funds that's something that could be left to the raid leaders to rewards the members who stuck it through to the end and did their best. Just have the raid leaders flag down an officer with the power to make it so and get the approval.


Ways to keep funds going into the gbank?

1) Donations. If people donate, good for them
2) Green weapon drops on raids. Instead of DEing these items for probably dust (which we have an overabundance of) they could be vendored for 7-15g and revenue tossed into the gbank. A few always drop every raid and every little bit counts.
3) Selling excess. If we have 46 uncut epic green gems then the odds of them being used up any time soon (considering we still get an influx) is pretty slim. If you were to sell 1-2 of those you could make 700-1000g easy. Careful trimming of items we have a serious overstock of (Arcane Dust comes quickly to mind) can generate a generous income.


Paying for respecs asked for by raidleaders to fit a spot.
Making up shortages or fulfilling requests by buying Hearts of Darkness and/or Nether Vortexs are also a good use.

Personally I think we should try to keep business, and ultimately cash, for raw and relatively easy to acquire goods in the guild. Instead of buying herbs or potions from the AH it might be better to just buy them from guildies.

Why buy Netherbloom off the AH when the guild has a number of herbalists?
Why buy food off the AH when the guild has plenty of fishers and cooks around?
Why buy potions off the AH when we have plenty of alchemists?