The 2005 was a good car but I guess it depends on parts availablilty if I would get this model.
If it were me, I would get the new M3 EVO. It's just a bit better refined then the M3. I have run all these cars & think the new M3 EVO is awesome!
Cheap Engine? Perhaps the RB C9, the new model Picco or the JP basic if they are still available. Even the standard Novarossi 35 Plus 21 is a good choice. Or wait till the new OS .21 onroad that will come out soon.