I don't know what you are wanting as to color, but Dupli-Color makes a line they call Paint Shop that is an old-style acrylic lacquer. It is available in limited color selection, but you could blend to get the shade you want. This is probably the lease expensive route, but also the least gasoline resistant.
Modern auto refinish paints (PPG, DuPont, House of Kolor, BASF) are generally catalysed acrylic-urethane enamels in either single stage or basecoat-clearcoat. These can be tinted to match any production vehicle by code number or spectroscopically matched to a small panel. You can still buy an etch primer for bare metal and high build, sandable primers, but the final primer coat should be a non-sanding epoxy primer. These systems are more expensive than acrylic lacquer, but the additional durability makes them worth it. Use a chemical respirator when spraying.
As any painter will tell you, surface preparation is the key to a good job.
I'm not an expert painter (or even very good), but I do know something about paint chemistry. (35 years in the business)
Ron L