Support pad not needed at all, more of an anti squeal item, but a light smear of copper grease sorts that out.
£148 way too much, you should be looking around the £50 mark.
Put a request in the "for sale/wanted" section on here for starters, lots of people have upgraded to the 1000 caliper so may have one laying about.
If maintained on a regular basis the 600 caliper is more than enough, but when neglected they go tits up. (technical term)