Originally Posted by Iride01

I find them all day long online for 34 bucks or less. Where are you shopping? While I like supporting my LBS, I don't usually buy from a LBS products that the bike shops can't get for any better price than I can.

You won't find a cheaper cassette by upgrading your groupset. However at some point your older groupset will run low on inventory and cost will go up. But I don't think that time has come for 105 5700 or whatever it is you have.