The Dulcimer Shop in Blowing Rock was started by Rogers McGee, and is now run by his son, Bill. It's a small shop but has a nice variety of items for its size. And Bill and company are friendly folks who'll chat with you all you want, as long as you give them a break when paying customers walk in!
High Country Dulcimers in Foscoe / Boone appears larger in it's website photos. I haven't been to their shop, but my wife as dealt with Mac McKinney over the years with various Girl Scout projects, and they, too, seem like nice people.
I'm sure both would be nice stops on your trip, but you might want to check their websites or call for their hours.
If you do plan to stop back in Black Mountain, besides Song of the Wood you might want to see if Tom Fellenbaum is around at Acoustic Corner , just around the corner from Jerry's shop. Tom's workshop is next door to the shop and he isn't always in, but you might be able to find out when you could visit. He doesn't usually have many instruments available to buy "right now", but hey, he's dulcimer folk! Another good guy to visit and learn from!
Another option is to see whether Don Pedi is playing around the area. If not, you might be able to catch his radio show his show on WCQS except in Boone, where they don't have a translator. Even then, you could listen online!