Well I got my car when I was 11 and have spent like $8000 over the last 5-6 years. I havent had a steady job and just have been selling parts, working for my grandparents, and doing odd jobs for any and everyone.
Overall If your careful with your money you can do alot, doing body work yourself really helps.
But going for a swap of one of the motors you listed gets pretty spendy even if your a skilled welder/fabricator.
Also if you go through the suspension and brakes when you get it the parts add up..
http://forums.hybridz.org/showthread.php?t=138753
I still havent gotten new pads which will be like ~$100.