Recently I needed to replace my car's battery (size 24F; I opted to upgrade to an AGM battery). In my town of 45,000 (medium-small?) there is one Walmart superstore (sans auto shop), a bunch of chain auto parts stores, and some non-chain stores. Shopping online, I determine:

   Walmart:  Everstart $180, 4 year "free replacement" warranty.
   Napa:     house brand $250, Odyssey $371  (both 3 yr warranty)
   OReilly:  house brand $250, Optima  $290  (both 3 yr warranty) 
   AutoZone: house brand $250, Optima  $290  (both 3 yr warranty) 

Walmart gets my business in this case as it does in most others. The few employees I interact with there don't seem to be unhappy, and their return policy is awesome (and is consistently applied). Walmart hasn't forced the competition out of business, but I see no reason why I should shop elsewhere in order to pay $70 (38%) more for an equivalent battery with 1 year less warranty.

Yes, Walmart is evil./s