Perhaps you're thinking of the Diaper Depot located in Atlanta, GA. I haven't been, but all indications are that the owner is *very* friendly, aware, and outgoing. My friend who recently visited talked with her for about an hour about what he looks for in a diaper and what he would want them to carry that she doesn't already. A few days after getting back home, my friend received a handwritten note from the Diaper Depot owner checking in with his experience post-visit and just overall being super friendly.
The owner also has a Fetlife page expressing her desire to cater to whatever her clientele wants to see her carry in her store. Very impressive and I hope to visit someday.