Used Turbo Source?

If someone wanted to do their own plumbing and design, and hopefully save some money in the process:
a) What is a good source for used turbochargers, (other than ebay)
b) How do you properly evaluate the condition of the turbo unit, and;
c) How do I determine which particular units are better suited to which design ideas?
On the last question, I'm looking for the broad strokes. I have different ideas, some for a single unit, some for twins; and the decision will probably be made in large part by what I FIND as opposed to what I WANT. I can come back later and ask specific questions. The second question is probably the most important.

First thing, figure out which JY turbos are good and which aren't worth the time. Garrett/AirResearch T04s are pretty good. You can make some pretty interesting combinations w/ the proper model. Next step is to find a repair facility or yard that handles a lot of them. I look for cores that:
-spin freely & have little shaft wobble
-have no impeller damage
-turbine housings in good visual condition
-have the least amount of balancing jobs on them

http://www.quarter-mile.net/images/turbo/P1010010.JPG
That's only half of my stash. I'd tell you how much I paid for them, but you wouldn't believe me. ;)

Mongoose -

OK, that's the kind of info I'm looking for. Thanks.

Anything to add?

If you want to be discrete, I can do this in PMs.