On a budget, the base and the transfer matter more than the room. A local-island guesthouse on an island reachable by public ferry or short speedboat keeps both accommodation and transfer cheap. A far-flung resort, even a 'value' one, can be undone by an expensive seaplane.
Know the local-island trade-offs: inhabited islands follow local customs, so there's usually a designated 'bikini beach', and alcohol is generally not served — many guests pair a guesthouse with a day trip or a sandbank excursion.

