There is no such thing as decent quality AND rattle can. If you want good results, there is no way around using the right stuff, and sometimes the right stuff isnt real cheap. You could probly paint the Jeep for $400-$500 and still have good quality.
If it were mine I would spray, the bare stuff at least, with epoxy primer then a 2k (2k=primer + catylist) primer after the epoxy flashes.
If you are undecided, and the parts are kept in a garage, you could just wipe them with Ospho (or whatever phosphoric acid) until you were ready to primer many or all parts.