Just like when prepping a weapon only one person can use it, is something similar that hard to script for the buyers? As for scamming and graal fudging up that's just a risk you have to take eh? It happens now anyways so there would be pretty much no change adding this menu.
As for being unfair that people can't afford the menu items, well, you can access GK can you not? What's keeping you from working one more hour a day for two weeks to buy all those nifty items? Some folks that left GK dude to it's getting old and boring just may return, you know they look at the forums now and then, i sure do, and when they see THIS added the'll be jumping on it like crack fiends, trials need not worry since they most likely never even had a taste of GK.
Just noticed you speaking of fairness at not everyone getting something, their are only a few of certain items now, the hammerouge, Ed's mage shield, a VERY few orc shields, only a few folks have the chance to own one through events, that could be considered unfair, why not make a new event and give anyone participating a shiney new warhammer even if they don't win? Just something to look at for a bit.