Not a plumber. However, if the guesstimate of the materials is roughly correct then he's charged you 60 squid for 4 hours work so that sounds reasonable if he's a pro.
For me that is value. if you do the math on it the labour as saint said if a registered contractor, then its quite cheap per hour. The thing is did you get a receipt/invoice with VAT etc on it? The part itself has to be right and the fittings have to be done properly. The repair was on the water side so its crucial that the closed system was maintained properly and you've no leaks. i presume you've checked there are no leaks.. though by know you'd know disastrously if there were. If you open a closed system to change a part you introduce oxygen back in so its vital they do it right.
Then you've years of hot water to look forward to and yer mate did you a big favor saying he'd not do it.
Can't be arsed digging up u21 thread as search is broken U21s won 2-0 Interesting line up. Bogdan, Randall, Maguire, Ilori, Jones, Stewart (McLaughlin 63), Kent (M Gomes 89), Chirivella (O’Hanlon 63), Sinclair, Brannagan (c), Ojo. Gomes only got on at end but scored last week for u18s. Watch for him. 4231 formation. Randall ilori jones Maguire Chirivella stewart Ojo brannigan Kent Sinclair.