I just finished mine with rattle cans on the outside. Can't say much for longevity (thats not what i'm after anyway), but it cost $400ish, that was all materials and cans. I used a lot of cans, much much more than I thought I would. Takes some time to set it all up, and at the end of the day I wish I bought a el cheapo compressor and paint, much easier coverage I reckon, my finish is patchy. If you go with rattle cans, make sure its a hot day, the hotter the better. My best finish was on hot metal. Mind you matte black is a bit unpredictable but thats what I found out. I didn't really cut much of the old paint, just sprayed on top.