there's a FFR Mk2 on denver's craigslist.
http://denver.craigslist.org/cto/2272545528.html
It's barely started and he has it listed for $11,000. you may get it for 10K and find a junk yard mustang for cheap donor parts.
Assuming you're real handy, and stick firm to a budget, have an available 400 or so hours free, and do everything yourself (including body and paint) you could, in theory, be driving a complete car for under 15K
On the other side of things, you just missed a complete, well built FFR for $12,000
http://www.ffcars.com/forums/showthread.php?t=266803
as you can see from the ad, it needed welding and either a rebody (Mr Bruce has an outstanding option) or a lot of body work. At $12,000 that was a deal!!! but it gives you an idea of how close you can come with your budget.
or you could sell a kidney and increase your budget