As of right now its really difficult to trade certain items. This is particularly the case for trade costume accessories or items with gems. The problem lies with the inability to filter by enhancement and also the price cap on the auction house on items with similar names even though they may have drastically different values.
I propose that a trading forum be created per server where players can list their items and other players can make offers in private or by leaving replies.
For example:
Telsiai
S> Fallen Angel Wing: Evasion 14, SP 103, Magic Amp 23
B> Fox Mask: Crit Att. 40, Crit Rate 15, Phys Att. 40