Had lunch with a guy once, to discuss an unrelated project he was working on. Come to find out he trained, too. Invited me to an Aikido club in his back yard, about a half mile from my house as the crow flies. He gave me directions to his driveway, which was hard to find. When I pulled into his windy, dirt driveway, I came to his house. Behind it stood a building about the size of a four car garage. It was built in traditional Japanese architecture. Looked like a little Kodokan. It was completely hidden by a grove of wattle trees. Inside was even nicer than the outside. It wasn't a commercial operation, just a group of folks doing Aikido.
If you have a million dollars, you can buy this home which comes with its own separate dojo building similar to the one you describe above. Picture ten is the dojo, which is my friend's house. And if you do purchase it, let me know because you'd live about a ten minute walk from me.
http://www.realestate.com/detail/368-1202926-3023-One-St-Honolulu-HI-96822/#