I know that automotive paint can be expensive, but there are some alternatives to expensive base coat clear coat systems. All of the major paint manufacturers such as Sikkens, PPG, and Dupont offer a by line of products under a different name. Example, PPG offers a line called Omni, you can purchase a gallon of single stage polyurethane paint with activator for around $150.00.
I used Omni on mine and was VERY impressed with how forgiving it is and how it so closely matches what would have been the original enamel look.
My paint job isn't perfect but I'm darned happy with it and best of all I can say I did it myself and saved a ton of money in the process.