There are a few sources in the U.S. who import. There is also a thread here on B'nut about ordering from Japan which looks promising.
FYI, The thing about any bonsai imports, including azalea, is they have to be quarantined two years before they can be brought into the U.S. Importers typically handle the importation paperwork and quarantine, some with quarantine facilities in this country, or in Japan. From what I understand the site selling in Japan direct to the U.S. has a quarantine facility there and the plants on sale have already undergone the isolation process.
@Bob Hunter might be able to help...as I think he's bought from them...From what I understand, You still have to apply for a phytosanitary certificate from USDA/APHIS to get the plant from that supplier--that process isn't as complicated, but it's a required step.
Also the quarantine/importation process involves barerooting the tree and fumigating the roots. That can take a toll on the plants. Some are killed by it. All that means prices can pretty impressive for imported satsuki, there's some sticker shock involved. The more developed the trunk, the more intense the shock.
