I can only comment that in Thailand it is super easy to find accommodation in the island, at least off-season. We could just walk around and just run into place

I can only comment that in Thailand it is super easy to find accommodation in the island, at least off-season. We could just walk around and just run into places that were very affordable. We found clean hotel rooms, small cottages right at the beach and nicer bungalows a bit farther inland all for $10-$20 per night. I imagine with more knowledge of our options we could have had even nicer places for the price. One thing I learned is that the 3G Internet connectivity advertised does not actually work in any usable way at least in Koh Samui / Koh Tao / Koh Phangan where we tried it, and had to rely on wifi. It was kind of a fun pastime to try to find places to stay in by scanning for wifi spots and walk to the direction where it gets stronger.