It's been about ten years since I worked in an auto paint store, so take this FWIW. As far as individual color prices withing a particular manufacturer's line, purples were the most expensive followed by red tones. Apparently those pigments were more expensive and/or difficult to obtain. Two-stage (base/clear) generally ran more than single-stage.
Call around to a few different auto paint stores. Generally speaking, the employees LOVE to talk paint, especially to someone that's not a professional painter. Try to call more than one store, since most will only carry a couple of brands. We carried PPG and DuPont, and were told to tell customers that other brands didn't measure up. I seriously doubt that that was the case, but them's paint store politics.
From what the professional painters that came in used to say, the brand of paint really doesn't matter; it's ALL about the prep work, and then just applying the paint correctly.
Also, many auto paint stores will have a "mismatch" rack...inexpensive pints, quarts, and gallons of all types and colors of paint that were mis-mixed by the "toner monkey". I know because I contributed quite a few gallons to this rack when the fumes got to me. Especially when it came time to paint my car and I needed a gallon of metallic teal.
Sometimes it's tough to find enough of the same color to paint a car, but since such a small amount is required for a bike you just might find a color you like for pennies on the dollar.
HTH
Jim
