Long time coming, but I'm building a little bracket car

Gotta say if you're looking at $400 cars, you're probably going to be in for some body work. And at those prices, at the very least you're probably going to be replacing every bushing and piece of rubber and on the car, all the fluid lines, brakes, etc.

Maybe build the drivetrain first, see how much is left in your budget then find a suitable body? Don't want to skimp on your chassis.