Having said that, I almost bought a black S13 with RB20 conversion for $10K.
it also had, exhaust, fmic, gtr injectors, rb25 turbo, remaped ecu, aftermarket radiator and large thermo fan, 5 stud conversion, R32 GTR wheels, R32 GTST brakes front and rear, R33 GTR seats, Tein coilovers, 17x9 mags which looked decent with lots of rubber, aftermarket clutch and flywheel etc etc..
basically, it was a registered, legit rb20 converted S13 with great list of mods for an asking price of $4K more than what your mate is thinking for his car.
get me?