You mention "the best". Best at what? What do you want to do with the car? Drag race, Autocross, daily cruiser? You want more original in appearance?
There are tons of cars for $35-40k, you'll just have to sacrifice somethings (mainly the engine).
Have you seen this site? There are plenty of Cobras for sale there.
http://www.cobracountry.com/home2.html