i've recently spent £100 on a cassette (XTR), £30 on a chain and £90 on a rear mech, some because of crashes and some through regular maintenance (awaiting fitting). XTR has always been expensive but in anyones eyes £94 for a middle chainring is a p**s take i don't mind spending the money, but sometimes its just too far.
so, a raceface or middleburn one for £30-50 is much more realistic