I'm going to be painting my calipers (and a lot of suspension components as well) just as soon as the rain lets up. The kit i'm probably going to use can be found
HERE. It's only $30 and comes with paint, rust remover, and a wire brush to clean the caliper with. I don't know anyone who's tried this brand yet but it looks like a good product. It has the same temp rating as the "G2" paint but can be sprayed on instead of put on using an applicator like the G2.
You might consider this product as well.