How much does a new 7 speed cassette cost at a bike shop?

[m.a818]

I just upgraded my crank,chain and rear derailer on my Giant.I then took my bike for a ride and noticed it skips once or twice.I checked the cassette an noticed it was worn down.How much would it cost for a 7 speed 11X28 7 Speed cassette at the bike shop?Quickest answer will get the best answer!Thanks.