I definitely need one rear so I'll get that of ebay. Refurbing the fronts will cost £30 and I'll have nice clean carriers too. If I couldn't get the plating done for free then yes, ebay it would be for the lot. Hopefully looking at about £120 to get all the callipers sorted.
EDIT: Oh hang on looks like you're right, seal kit and pistons for the front is £45 plus del and you can get em on ebay for £53 delivered. Oh well some more disassembled metal to weigh in then!