Mine is definitely a 1993 Saleen SA-10. Although I'm probably stretching the "attainable" criteria a little since there are only 7 or 8 left in existence, and I'll likely never afford the prices that they fetch.
Other than that, I desperately want to get my wife a Mystichrome Cobra one day.
1968 Mustang GT/CS with GT options, Red with white stripes, 390 4V, 4-spd (S code). When I was going to highschool, the guy across the street had one. Drove it past me every day while I was walking to the school bus. He also had a 442 that he only drove to-from and at the drag strip.