The only repro warbirds I have seen are 2/3 scales repros, a few mustangs done like that. Those are pretty cool.
For the real thing, you are talking millions.
2/3 reproduction P-51 Mustang
This is a Stewart S-51
built by Dan McGarry.
The Photo was taken by Jim Klick
from an old, fully restored, T-33
Stewart S-51 Builder's page
2/3 p51 (S-51) In flight.
The Stewart S-51D is an all aluminum replica of the North American P51-D Mustang at approximately 70% scale. The aircraft was designed by Jim Stewart over a period of about 20 years, and was offered as a kit in the late 1990s. It is normally powered by a big block Chevy V-8 engine in the range 454-573 cubic inch displacement. These engines normally make between 400-600 hp at 4750 rpm.
Chevy 454 in the air ain't nothin to sneeze at.
Sweet Video of the S-51