Gheyness or not.. here's my pricesheet for turboing:
There are 3 EXPENSIVE parts to a turbo setup, the turbo, the manifolds and the management system.
The Turbo: you can get a used T25 off of Ebay for $100 for one that needs rebuilt (then put another $80 in parts and $225 in labor into it), or get a refurbished one for $300.
The manifolds: If you have a stockpile of aluminum sitting around and a Mig (and know how to use it) you can build your own intake manifold for a hundred bucks in misc peices. If you have to have one made, you're looking at $600 to $1000 for a custom setup.
The Management System: If you add more air, you gotta put more fuel in. If you dont add much air, you can just bump up the fuel pressure to your stock injectors... but what fun is there in THAT?! A standalone Boost-Sensitive Extra-Injector-Controller will run you about $300. Add a two-bar MAP sensor, a wideband O2 sensor, a boost gauge and an o2 meter and you're looking somewhere around $1000 all together. For another $500 to $8000 you could go with a full-stand-alone ECU that will eliminate your stock ECU and control all of your stock Injectors, timing retard, and you can even get something with traction control.
You're already somewhere between $2500 and $10000... and you haven't built your exhaust manifold yet, your fuel piping, your exhaust interconnect, located a spot for an itsy-bitsy intercooler, or beefed up your motor to handle all of the 'huffing' you plan on doing.
Or... for $4500 you could call Mr Turbo or one of the aftermarket manufacturers of sportbike turbo 'kits' and get yourself something already-built.
Phil