I've been searching a lot of home and hardware shops in town and wound up at the local Ace Hardware store. It turns out that they have an acrylic enamel paint, Rust Stop, that comes in a wide range of premixed colors as well as the ability to custom tint.

Direct quote from the brochure reads as: "Ace Rust Stop Enamel is ideal for use on metal. . . This card presents a palette of ready mix colors, complemented with a select sampling of custom tinted colors. See our Ace Paint color display for hundreds of additional choices."

The sales brochure features over fifty different colors and it only runs a little over twenty bucks a gallon.

Just an FYI, since so many people feel limited by Rustoleum and Brightsides color restrictions.