Try a single stage paint out. Usually you buy 3/4 of a gallon and then mix 1/4 of a gallon of hardener in with it to make one gallon. Usually they go for 70-110 dollars a gallon mixed. SS is most often found on fleet vehicles and if you use decent paint and good prep as well as cut and buffing, will be on par with BC/CC. BC/CC is a 2 stage paint that is the industry standard for cars painted today. BC/CC means basecoat/clearcoat and what that means is a color coat is first sprayed which is pretty much all pigment (color) and looks flat (no gloss), and then clear coat is sprayed over that.
Save what ever is left over (unmixed) and then buy one of those refillable aerosol cans and touch up parts when ever you need to. The can's I'm referring to are pretty common in construction, you can screw the cap off, pour what ever you want in, screw the cap on, then put like 30 psi into the can via your air compressor and then its ready to spray. You will have to clean the can out though after touching up pieces because the paint uses an activator/hardener.
An alternative is to use a tractor paint... Gets very hard, much cheaper but limited colors and doesn't require a hardener although one can be used. It stays tacky for like 2-3 days (dries very slow) however and the color pigments tend to be weak. I use black gloss often on parts that go under my jeep because it's not seen that well and is pretty indestructible for the cost as far as liquid painting goes (vs, say powdercoat). You'll need to reduce tractor paints to shoot out of a gun though as they're thick and meant to be brushed on. I just use lacquer thinner since I buy lots of it for when I paint using BC/CC
