Cost of the car itself will cost anywhere from $600 (If you start with just a shell or it's in really bad condition) up to $3000. Any higher than that and your paying too much for a 1992 Civic.
In the end though it'll cost much more than $3,000. You have to also take into account the price of the turbo kit, the price or rebuilding the motor, getting the car tuned, the new ignition a turbo will require, a better exhaust system, etc...Plus at least another $1,500 if you swap out the current D series engine in the car for a B series. Haven't even begun the tool prices yet for anything you don't have or can't rent.
Best options to get to a turbo imo:
A) Look for a 1992-1995 shell or a Civic with just no engine so you can have a fresh start and buy whichever engine you want then go from there. http://www.hmotorsonline.com/shop/
B) Find a 1992-1995 EX (D16Z6 motor) that is running pretty good and rebuild the motor with better internals and work up to a turbo from there.
C) Buy a 1999-2000 Civic SI and turbo that baby! lol
One thing you should do before ANYTHING else (Especially on 1991-2000 Civics) is buy a new security system, or lemme rephrase that. Get one *professionally* installed. Not some crappy Best Buy one that is thrown under the dash where it's easily accessible and can be dealt with by any thief in 30 seconds or less.