The JLI trades are really crap quality (especially #2), and they never finished collecting it all. New collections would be most welcome. DC has started to solicit a bunch of trades from the later part of the run (still leaving a gap though), so if they sell adequately I think there's a chance they'll go back to the start and finally give it the collection it deserves.
I found vols 1-4 at a used bookstore but had to pay full cover for 5 & 6 at a comic shop. As far as trades are concerned, in my experience you can usually find anything that's expensive online out in the wild for cover or less, eventually. Still haven't found an Avengers Trial of Yellowjacket trade yet, but everything else from Nova to Vengeance of Moon Knight to Stephanie Brown Batgirl to Kyle Rayner Ion to John Byrne Superman #4 that I've wanted but couldn't get online for a reasonable price, I've found and usually for half off. Even Daredevil Fall of the Kingpin, the old 90s trade, in perfect condition for $10.
Well, that's not true. I did find a Trial of Yellowjacket once but balked at paying $40 for a trade. Went back a few days later figuring I could always resell it if I didn't think it was worth the money after I'd read it, but it was gone. Ah well. The hunt continues. I'll spear it at $20 someday. Probably as soon as it's announced as an Epic.