Before you decide against this plan, realize that cost will depend largely on what turbo you get. There are some cheap Garrett T3s on Ebay that could probably be used. Yes, they're intended for 4 cylinder applications, but a buddy and I were talking about them and he thinks you could make positive boost by putting one on an L36. Heck, you could always go twin turbo with two of those cheapies. We figure the best way to do it would be a cheap turbo mounted in a remote location. If you do most of the work yourself you might be able to do it for $500-$700. Give it some PEMs and a chip in addition to the turbo, and you're sitting pretty. Probably not a 13 second car with a small turbo like that, but then again I really don't have any good estimates for how much power you would potentially gain.
What do the rest of you think? I'm I full of crap, or could this be feasible?
This is a bigger turbo than I had in mind so it costs more than what I estimated, but it might be a good match.