When the time comes to add an AH or market (whatever you have in mind), I think it would be good if it also supported bartering.
Few people sell gems anymore, most prefer to trade. Same with other high level mats. It's even true with low level mats. I much prefer to trade plaice for carrots or ginger then sell and hope I can buy later, even though both go for about the same 15g/100. (Anyone selling or trading carrots or ginger?)
Perhaps once we have a market or AH the economy will change, and this will be unnecessary. And it adds a fair amount of work. But as things stand now, barter often replaces the ep/gold economy.