Is this fantasy trade screwing me over or is it pretty good?

Well I think this trade is a good trade. But you need to judge this based on how much you need a WR. It sounds like you have a good RB core. However, if you feel you need another receiver I would take Jericho Cotchery and get rid of Lawrence Maroney. The thing is, you have 5 RB's. You don't need that many especially if they are that good of a group. Trade Maroney and ask for Cotchery. Mason wouldn't be a bad deal either, but he isn't getting as many yards as he was in previous seasons due to age and lack of Baltimore offense. At least with the Jets they already know Cotchery is their leading receiver. So go ahead with the trade.