I have to say that some of you guys seem to take this way too seriously. I bought a can of 'Ferrari Red' caliper paint from eBay and a spray can of brake cleaner. I took the wheels off, cleaned the caliper up with an old toothbrush and the brake cleaner, then just brush painted the caliper paint on. You can't see the piston side without removing it anyway, so what's the point in painting that side.
A few days later when it was all dry, I then stuck on the decal, and brushed clear lacquer over it with a clear-coat touch-up stick from Halfords. 3 years later and it all looks spot-on still.
There's no need to remove the caliper from the car, and there's no real need to start painting inside the holes for the pins etc either. With the wheels on and the caliper down at kerb-height, it looks exactly the same as one that was removed entirely and oven-baked etc etc.
The things that are worth spending more time on are cleaning brake dust (etc) off, taking care around the edges of the pins and the pad area, and getting the decals on straight. I think the total cost was about £25 tops.