I've found a nice refurbed set of BBS R90 split rim alloys for sale

The dealer is after £500 for the set minus tyres, is this a good price? Am I right in thinking these alloys were a very early option with Minis? I saw the Italian job last night and they featured on there!
My question is, if the alloys have been refurbed can they be refurbed again and again? They have the diamond polished rim, im guessing they have to remove some metal to refurb, only so thin they can go!!
cheers in advance for any help!!