For the most part, you can keep wheels clean with the same soap and water you wash your car with. For extra-tough road grime and brake dust, those special cleaners like Meguiar's All Wheel cleaner work well.
Thanks all. It looks like 50 Resto is the best deal on machined 03 Cobras. However, BuyFordParts has the cheapest M2300K brake kit price I've seen ($2199).