Well, there's only really one substantial gallery there--Kamakana Gallery--and he has a bin full of prints there last couple of times I've been there. All inkjets as I recall. I don't know how well they sell, there not being as much tourist trade on Moloka'i as on the other islands. I'd be surprised if he didn't also have some work at the Sheraton resort gift shop and maybe at the Big Wind Kite Shop, which also sells folk art, books, and other things. He had a piece in _Outdoor Photographer_ maybe a couple of issues back about cultivating aloha by giving away inkjet prints to locals on the island.
If you get out there, do check out Stanley's paintings. They really are stunning in person.