theres some autoparts stores that sell paint... if u can find one that mixes it, you could get them to mix you some tractor and emplement paint... its cheap and holds up well
its just the fact of finding a color that i want. i know its not that important but if i spend all the time building it i want to paint it something decent no matter how long the body last!
When I lived in Houston, TX I had a buddy that worked at O'rileys and he could mix any paint I wanted and put it in either a normal can or a spray can. So you might try an auto parts store that mixes paint.
Go to a PPG place, get the color mixed in acrylic enamel... The paint shop should carry a small inexpensive kit that uses a glass container and disposable air/co2 cartridges that work just like a spray can, but better... Did my whole samurai this way years ago... There is a place in Boone that does it...
Then again, I wised up and went for rustoleum after a few years because im lazy....
Sounds like you might want to consider just having Maaco type place to mix and paint it the exact color you want.
As far as putting in spray cans, why? If you own an air compressor already (or a buddy who does) then you can get the exact paint mixed at someplace like o'reillys and then shoot it.
I throw this out there every once in a while for folks wanting to paint their rigs, it is an article I wrote a couple years ago now about painting my rig for $80.