Rod, funny you should ask as I have been on the same mission for a while now. Custom painting is crazy expensive and then you add in the cost of the helmet itself. The painted helmets on ebay and craigslist are all junk or very odd.
I did however meet a guy at the track that went about getting a custom helmet by calling the paint shops and letting them know he was looking for a good buy. Turns out a shop just finished a helmet that the owner bailed on payment so he picked it up for a fraction of the cost. I have talked to a few shops and dropped my info in case one of these comes about, or even one that had a minor imperfection, we’ll see just have to be patient.