Everyone is SO nice here. I'm having one of those days so I'll be "that guy."
You just CANNOT do what you claim to want to do, for the money you claim to want to spend. Sorry - someone needs to say it.
And please don't buy into the stories about building a $5000 spec [whatever]. You could build an e30 with required safety equipment, suspension, original paint, a pretty good replenishment of worn-out parts, and reasonably healthy junkyard drivetrain - if you do all the work yourself.
For some reason, those guys who tell you you can build a [whatever] for $X always seem to want $2X when it comes time for them to sell theirs...
...until they finally to the point where they take $.5X, which is where they should have been from the outset.
Based on what you've given us, you have just a couple of choices, most of which have been described:
Toyota MR2
1st-gen RX7
I'd add the Toyota Corolla GTS
RWD in ITB??? Hmmm..Porsche 914 and the Volvos, and Alfas.[/b]
You are a bad, bad man, Jake for even putting any of those choices in writing. You want our new friend to still be around in 2 years, right?
K