I have a set of Discovery adjustable dob bearings from a Discovery 12.5" PDHQ. The bearing surface is the standard Ebony Star and is in perfect condition. The mount plate has some nicks, but this piece does not interact with the bearing motion, so it does not effect performance. According to Discovery, these can fit on tube size of 12" - 18". Pictures will be sent on request. I figure the shipping will be $10-$15 USD given the weight and size.
Discovery sells these new for $130 + shipping, so this is a steal as they are coming off of a 1 year old scope.