Hello Breci,
I am one of the original elder members of the R2Builders Group (can supply link in PM). I have built a full scale working R/C R2 (see attached link below) I do have plans that you could use to make a quick scratch built R2, I also have an R2 pepakura that you could scale up a bit and re work to suit your needs.
I can tell you though, that a good replica will be at least $500, and goes up from there based upon your resourcefulness.
~James
http://photos1.blogger.com/img/170/7637/1024/Img_3164.jpg