As has been mentioned before in this thread....the affordable option is the Titan Mustang but the kit leaves much to be desired...very lightweight, poor component design (nothing fits properly) and although advertised as a "first time builders kit" it really doesn't seem to be...and I wouldn't even toy with the thought of putting the Falconer V12 up front, it'd rip the aircraft apart!!
If you want a REAL toy then the Papa51 (Thunder Mustang) must be the ultimate...beats the original aircraft in every respect except weight...and a REAL V12 up front...trouble is you'll pay more than an authentic one to get one in your hangar.
Take a look at "Tiger's Blood" on
http://www.kiwithunder.com
[Edited to get the link right]