Wow, it looks like you enjoyed quite a variety of the restaurants that Okinawa has to offer. I don't think those places seem very cheap though! When I read the first line of your post, I was thinking something completely different. I haven't been to that gyro place either! I always see it and want to try it, but I haven't had the chance.

Anyway, I'd say all those places are more expensive than eating Japanese food at home, but there are a lot of Japanese style restaurants shokudo that offer food for very low prices. Maybe 200 yen for a bowl of soba or something. These places are at least as cheap as the food I make at home, but I can probably get more variety and a healthier diet by cooking at home.