Nova Tropicals is gorgeous. They do have a betta selection although stock seems to vary - might recommend calling them first to see how much they have in. I definitely recommend checking them out. Even if you don't find your dream betta there if you go, it's still a great store to look around. I didn't end up getting a betta from them, but they're probably my first choice if I decide to restart my tank at some point

I got a betta from Tropical Lagoon in Silver Spring and it ended up having really bad ich which was kind of a pain, especially because I'm new to the hobby.