Forget the limited selection of magnetic paint colors. Instead, you can prime surfaces with Rustoleum Magnetic Primer, then paint on a topcoat in any color you please.
This could be used on kitchen cabinets to provide a magnetic storage surface. Or it can be used under chalkboard paint to create a chalkboard/magnetic message center.
The primer color is a dark charcoal, which makes us think that several coats of light-colored paints will be required to achieve full coverage.
It goes on with a roller like any latex paint. The price (as with most specialty paints, it's not cheap) is about $20 for 32 oz.