I've played quite a few MMOs, and often spend much of my time in the trading/crafting areas of the game (which was one of the reasons I joined Glitch).
Unfortunately, the economy in Glitch seems to be a bit broken in some areas.
The most obvious one is for items which can be bough from vendors. In this case, with max upgrades the spread between buying and selling is only something like 30%, and vendors generally have unlimited stock and will buy unlimited amounts.
This has an awkward interaction with the auction house cut which is large 7%.
Thus, if you want to make and sell something in the auction house, there is only a tiny window of prices which make sense. If you want to sell the item, it really needs to be at least 10% less than the auction house price, or players will just buy it from the vendor. As the auction house fee is non-refundable, items really do need to be priced to sell.
At this price, after the auction house cut, there is very little margin over just selling the item to the vendor. If the item doesn't sell then even that is wiped out.
This leads to a very stagnant economy in many items, most of which are simply not worth making.
Having vendors is admittedly useful for new players, but the narrow spread between buying and selling is bad for the economy. Most other MMOs I've played have a much larger spread.
This could be resolved by enlarging the spread, removing more of the vendors or reducing the auction house fees.