It isn't a ripoff if you paid the price.
NAPA's counterman can pull whatever attitude he wants. His or NAPA's loss or gain.
Capitalism.
Lots of local auto parts places to use for me. However, when spending a month at the cabin, the closest supply house (of any kind) is a NAPA store....and they always have whatever is needed and occasionally they run it to the end of the road (where I pick it up with the SxS). While I care about price, that sort of availability and service covers a lot of markup and makes the switching cost not worth it.