I think you are way off base on you cost estimate. You forgot radio. There's noooo way you are going to use a standard radio on a plane like that. You need a top quality radio for a plane like that. I'd say $600 to $1000 for a radio and the same amount for quality servo's. I am in no way saying this to be mean, I am only bringing this up because my first giant scale model (the 27% Extra in my avitar) was VERY expensive. Way more than I planned and I didn't have any scale details to speak of. I have almost $2000 in my Extra. Why?

$250 Plane
$350 Radio (JR XP642)
$400 Servo's You can't use standard ones on a plane like that.
$450 Moki 1.8 engine, muffler, spinner, spinner nut on and on...
$500 Of nickel and dime stuff like pilots, 7 rolls of covering, fiberglass parts, servo reverser's, fuel fillers, on and on.....

Please don't take this as a negative post. I'm just trying to save you the sticker shock that I had. Your engines alone will eat up the $1200 number. I would start at tripling your figures and go up from there......