Cheapest mail order I can find is ?100 and my local ATS depot would charge me about ?15 for fitting.
Just out of curiosity I phoned Woods Motorcycles in Abergele. Supplied, fitted and balanced for ?119 to a loose wheel so it doesn't look like its worth the hassle of waiting in for the post etc. I pass the shop regularly on the A55 so it isn't out of my way.