What makes this so important is that Ra was both prolific and obscure, and there are bound to be recordings from the archives that are nowhere to be found via the direct or after-markets. Check the link above for schedule and listen as much as you can, because nothing and no one explains the weird, contradictory, insane and beautiful roots of American popular music like Sunny does. Here’s the essential primer, and I do mean essential, this needs to be in your music library.
UPDATE: The iTunes store has set up a page with a substantial collection of digital releases. (h/t Hank Shteamer)