I see values in all of them, but mom and pop need to get specialized or go out of business. I know a couple mom and pop end up doing more online businesses for doors and windows replacement hardware sales than their store front sales, and carries (or middle man) those they don't from their wholesalers.
One thing nice about large box stores like HD and Lowes, they don't as too much questions about returns like the mom and pop, because they just charge the manufacturers back.