That's WAY over the top! I can't find the link now, on laptop and the mouse doesn't want to play but I know somebody reckoned around £40 tops - half an hours work at most. Try shopping around - if you're out of warranty then the last place to go is the main dealers.......
cheers grey, yep, the pads themselves are very cheap, like the link says shop4parts do them on discount for forum members, and you'll find it very easy to change them over yourself