Consider that you will need 4 coats. I would buy a gallon of color and a gallon of black. Consider this paint as it will save you $$$
http://www.tcpglobal.com/restoration...chsheet_au.pdf
I've used both ppg(1 car) and Restoration Shop(2 cars). IMHO the several hundred dollars difference in the cost of paint isn't justified. I've also use Southern Polyurethane primer to good effect. IMHO the at least $1,000+ for using all ppg isn't necessary.
Good to hear you are considering single stage. I finally figured out the practical difference between it and base/clear. With single stage to fix a scratch you can simply dab on the paint, sand and buff. With base/clear you have to re-apply clear on the whole panel.