Ah, someone had mentioned this and I forgot all about it. Thanks for bringing it back to my attention.

I became interested in Okinawan when I came across a guy selling Okinawan books on eBay. The one he sold me was a picture book geared towards Japanese speakers called. I think there were too. I also bought a primer on Amazon.Co.Jp. I was supposed to buy one that teaches Okinawan via manga (kinda like the now-defunct 漫画人), but that never panned out.

Now if only someone would publish stuff in English about 제주말.