Use jsp. It has its legions of idiots/hackers/dupers/whatever but if you stay away from them/overlook them then it is actually a very active place facilitating almost constant, instant trades for anything you may need. Just sell any random low/mid level items you find and use the fg to buy whatever you may need. Works a lot better than the trading forums here, trying to trade in-game or anything else.
Alternatively get to know more people. High level mfers amass heaps of low/mid items incredibly fast and most would gladly give away a lot for free if they know you.