well, it's not brand new. It's a 97' or there about.
Sure you can get a motor for that price. But what about wiring harness, ecu, all sensors, ect, ect, ect. There are usually lots of "little things" you end up needing that might not be there if you get the motor second hand.
Also, i should have mentioned... If I put it in my ZX I have to leave it mostly stock to pass emissions. If I put it in a S30 I can go all out.