My last PUR filter's light has been flashing red for a couple of days, it's already tasting wonky, and before long it's going to be back to totally gross.

Usually I grab replacement filters at Publix or Target. Does anyone know who has the best deal on these?

This is the filter for the tap (vertical), not the pitcher. Like this:
PUR 3 Stage Faucet Water Filter Replacement

Edit: Might I do better by ordering these online, like from Amazon maybe??

TIA