Why buy ammo local?
I get it, there's AmmoSeek and other sites that watch for deals and availability. There's also shipping included and wait times. For the long term stock pile it's just something your local shops may not wish to compete with.
The internet doesn't care you bought .38 Super+ instead of .38 Special and there's no returns on ammunition in almost all cases (it's a liability issue). Another example - a really good buy online but it's steel cased ammo...great price if you don't mind the destruction of your barrel.
However, you never know what your local shop may have unless you go and check it out. Most of us do not want to deal with the hassle of shipping hazmat materials and don't have great breaks on shipping, so what we've got is in the store and not listed online.
And sometimes...there's an estate that comes our way with a boon of hard to find ammunition. Lot's of it!
So if you're running to the range and need a quick box or two, looking to get your specific caliber ammo right before leaving on a hunting trip or just like the experience of talking to a person that will make sure you buy the right caliber - you local gun shop is where it's at.