Where can I get bogie wheel covers cheap. The rear wheel has a yellow cover, but the front two are black, I would like them all to be yellow. I thought about painting the ones I have, but the yellow ones would work better.

You have to buy the entire wheel.
Royal has them for not much money.

Those screw on covers are a pain and look cheapo. Take the fish's advise and by a couple from Royal, they aren't much money.
:)
Rick.