Duplicolor and Plasticote are the most readily available decent quality spray can paints. Durability will jump exponentially when you make the step up to a urethane clearcoat(which is sometimes available in spray can) which will be best sprayed with a gun. The purpose being, the gun-sprayed clear will require the hardening agent to be mixed into the clear and will have a limited work time in the gun before it hardens. This is why it will harden faster and more thoroughly than the can-type which has no hardener.
The Martin-Senour paint system is what we used at the car restoration shop, which is available through NAPA Auto for a very respectable rate. DO HEED THE SAFETY NOTES however. Professional paints are fun to work with and make lovely results, but they do need to be treated with respect.
Generally, clearcoat should be the identical system as the color(though there are crossovers, listed by the paint mfg or shop) and applied within the "tack range" of the color. This is so that the evaporating hardener and solvent fuse through the clearcoat(not to be confused with blending of the color), producing for all real reasons a solid chemically continuous layer. This applies to both enamels and urethanes.
All paints on metal will benefit from a heated dry time. Factory paint shops, both automotive and bike are heated to 70f to paint, and turned up (around 150f) to cure immediately after application. When it is immediatly following application(particularly with urethane(which has a slower dry time at first) it will make the surface "flow" into a glassy smooth shine. Well worth it if you can figure something, not to mention its safer to handle without scratches when assembling.