Well here is the way I look at it, dont buy a used turbo kit expecting to run it bolt on when you get it. Not going to happen unless you dont want it to run very long. Just expect you're going to have to either have the turbo rebuilt, install a new center cartridge, or flat out buy a new turbo for it.
However, I've seen these kits sell on ebay with turbos described as needing rebuilds sell for over $700.