What does it actually cost to have brake pads replaced?

Really, if you're that tight that you want to "have a go" at this sort of stuff, maybe you should stick to your VN Commodore.
It's your BRAKES, for Gods sake!
It's this sort of crap which explains why Ferraris are worth about 5 cents in the US.
ie. every knob with a spanner has a crack at "maintaining" them, and then they wonder why they all blow up.

Disclaimer: if you have mechanical knowledge and know what you're doing, fair enough. But then you wouldn't be reading this thread anyway...