Singles, Trade or...Online?

Just this evening I've managed to read 2 volumes of Ultimate X-Men recently downloaded via IMesh. Volumes 3 and 6, to be exact. I would've gotten volume 5 (The Ultimate War) but I already ordered the trade. What's frustrating is now I'm left with a scattered collection of UXM trades that proabably weren't worth buying in the first place, discounted or otherwise.