I think $2000 would be an okay price for a good condition SR20DET BB. You'll be looking at $3,500 for a SR20DET BB, ECU, Wiring harness, SR20 5spd transmission, Axles, Clutch pedal, Master & slave cylinders, and the whole works to go from an automatic to manual.
www.highperformanceonline.com was talking to me about all the stuff that was needed. It gets pretty pricey if you have an automatic. ( I love automatics but I hate the prices )