Bears38, about any auto paint supply store can mix a rattle can. Here in Wichita there is an O'Riellys that does it.
As for painting with a rattle can, the quality of the job depends on how much work you put in it. If you sand like you should with a spray gun job, you can get a decent looking finish. Also, if you want a rattle can job to hold up to the elements, finish it with a clear coat.
