It doesnt cost too much to replace the head gasket if you are prepared to do it yourself. i bought a zr/25 a couple of years ago with a broken gear box (no 2nd gear) which resulted in the engine being over revved in first and blowing the head gasket. it cost me just over £150 to buy a new gearbox, gearbox and engine oil, uprated head gasket and a new timing belt. Worked like a charm for well over 20k miles until i sold it. the only other thing id be weary about with these cars is the cooling system. the tend to fail quite often and clog up. I you get a good one then year, theyre amazing cars, but i wouldnt buy one thats done over 60k miles.