Replacing front discs

Hi guys i've got a pair of new front discs because mine appear to be nackered! how much wud it generally cost to it these? the garage who fitted my diverter valve sed £30 and it would take then 15 mins..... so ummm that means £120 an hour?!lol something doesnt add up here. it seems to me like they might just wanna over charge me a little! and NO, i'd rather not attempt it myself at all!lol cheers /ubbthreads/images/graemlins/grin.gif

unfortunatly i don't know how to do any of it. i cud give it a go but wudnt want to mess up half way and then be up sh*t street!haha. cheers guys