I love a good deal like most here too. I can't afford to ignore pricing. It's not just the price savings though. Here's why I think the mom and pop stores are suffering (among other reasons).
I'd have to divide my shopping into 2 categories.
First is when I need to buy something for a replacement or fix.
I usually need it right away so buying locally at the most convenient place with a knowledgeable person to help me is my first consideration. I could care less about price about that time. I'm already PO'ed because I have to do this (especially if it's plumbing on Sunday) so I want to get a good replacement ... the right one ... and I want it now. I would love to have a mom and pop store right around the corner for that. Maybe even send the kid over to get it while I stay working under the car or something? And have the owner or help be well versed enough to make sure the kid gets the right thing.
Next is the shopping I do for something I want. In most cases you've already determined what product and quality you want so it becomes a price thing.
That's where the box stores will offer (in some cases) substantial savings the item. The other draw is the convenience of all that other stuff that's right there for you to buy or window shop. You might be able to pick up this or that while you're there? You can pick up a tool or a video or a TV and tires and oil....even groceries all in one place.
Another thing, at least in my area, is the burden the traffic imposes on a guys brain. I hate that sooo much! For me it's a PITA to go anywhere anymore. So why not try to stay out of it as much as possible by going ONE place to get it over with? Not to mention how costly it can be if you have to drive some distance to several places ... and run the risk of them not having it anyway?
The internet is fast becoming my favorite way to shop for things I want and shipping is well worth it keeping me off the streets. Even more so than the big box stores. I also tend to buy only what I want and not get suckered into buying all those other things. But for convenience and quick, good help, you can't beat the guy around the corner even if he is more expensive. I miss being able to get to them easily too.