I know you said UK based BUT this ebay shop is fantastic. The parts are dirt cheap, the postage is dirt cheap and Ive had stuff come in 5 days!
£4.81 For a pair of fronts +£1.25 Postage. Thats the Ti Nitride coated ones.
http://cgi.ebay.co.uk/Tamiya-TRF501X...4.c0.m14.l1262