Yeh, I did a search for AMT '63 Tempest sedans (I assembled and built glue bombs) and they're crazy expensive (~$200 - $400).
AMT has re-popped their old "Craftsman" kit for the '63 Nova wagon - a possible candidate for the chassis/ interior.
I totally understand your point about dumping too much $$$ chasing a kit bash goal. I'm about $100 into aquiring kits, parts, decals, paint to do a non-AWB '65 Mustang AF/X cammer (Brannan's Goldfinger) and will likely end up with an imperfect mix of 1/25 and 1/25 parts. Chasing scale modeling fantasies can be $$$.