I did try a Wish economy once, but the trouble is that Scrolls are cheap. Basically everyone and their familiars with UMD gets full casting, only with unlimited slots and every list. Unless I missed a houserule about dealing with those. Also, there are tons of minor items that grant an effect that's useful at all levels (move 10 feet as a swift action, etc), and they can be made slotless with little difficulty, which also tends to cause some problems because everyone in the party gets a few dozen of each. Again, unless there's a rule on maximum items used simultaneously.