If you don't mind it not being the car you have now, look around for an unfinished project. I have just bought a '79 sunny with an SR20 conversion almost done and the body is all prep'd for paint for $4000. It might not be the car that I started with but if you take into consideration that a front cut is about $2500-$3000 and I would have to get a panel shop to do the body work and all the time spent on engine mounts, tail shaft and so on, I am saving about $3000.
But that money has since been spent on an Autometer dash and R31 diff and the list goes on.
Either way the end result is much worth the time and money, seeing the look on some dudes face as his SS or XR8 is being ass wooped by a datsun