i've found aftermarket drum pads online for like sub-$90 a set. if you're willing to fit them yourslef, go for it. they are drums, and not that hard really. That said... the above looks like 3-4 hours labour, (about right if they intent to flush the system...) plus pads and markup.

if you can find the instructions online, (google FTW), and know how to spin a spanner, give it a go.