I did race deck, awsome stuff. Thankfully I found some used on Kijiji when I was looking. Costco also sells a product called motofloor which they sometimes have instore. IIRC the cost per sq foot is close to the glfoor roll's.
Nice thing about the tile systems is if you mess up a tile you can swap in a replacement tile easily. I would definetly NOT do the paint, unless you etch and etch and etch that floor, any old floor is going to have issues. The consumer grade paints/epoxy stuff we get will not hold up over time. I've seem them fail time and time again, very few have done the proper prepwork on the floor to make it last. I do work in my garage, welding, fixing my cars, etc the epoxy floors never seemed to hold up. After 3-4 years lots of hot tire pickup, burn marks, etc.