I have a need for a small amount of hard wood flooring for a repair job in my house. So I am calling everyone local who might stock the stuff in the size I need. I called ProSand, and when I explained that I didn't want more than 1000 square feet of it, they immediately terminated the conversation.
I love shopping local, and ProSand is approximately local (several stores in Indiana). However, a distinguishing feature of local shops is that they love to help you out even if they aren't going to make a ton of money on you -- if they have the stuff in stock then they'll sell you even a small quantity because they know you're much more likely to give them referral business.
For example, I shop regularly at Bender Lumber. I know they make most of their money off of contractors who buy in volume. Nonetheless every couple months I wind up in their convenient store front near downtown Bloomington, and I will be buying very small quantities of lumber. They are always courteous and helpful even when my requests are unrealistic.
Bender Lumber is an example of how local shops ought to act. They rule.