Here's just and idea that worked out well for me. I bought the BAT Inc blank rotors and some good, high-quality, high-temp paint - black. I masked off the braking surfaces so I could paint the center portion of the rotors, sprayed them, carefully pulled off the masking, and then they went in the over to bake the paint on. Initially, I wasn't too condifent it would last but has it ever! The baking process really makes the paint adhere well to the rotors. The key I think is cleaning them really well before painting - make sure you get all of the oils off, then repeat the process to be sure.
If I had it to do again, I would have painted the outer circumference too - at the edge where the cooling vanes are, there is rust now. It's not easy to see, but I see it and if I had painted it initially, it wouldn't be rusting.
Worth a try if you don't mind the stink of baking paint for a few hours in your house. Really, it worked great and I was able to keep the non-slotted rotors and get some good looks out of it too. The paint was the 1500 or 1200 degree stuff from the parts store - it says on the can too, bake it on if you can cause it will stick much better if cooked on.