It really isn't that expensive. Have them blow it up to O Scale - 133%.
My #3 is an AC8 Cab Forward, done by blowing up the drawing in the MRR Cyclopedia to 17/64 scale on Mylar. After I finished, I framed the drawing. I think it was three bucks, but that was 35 years ago. They took a photo with a precision camera.
Since then I have done dozens using Hundman's drawings, but usually just have them xeroxed. Around 17 cents each.