In Poneloya (Nicaragua), many hotels offer decent accommodation for a mid-range price.
The first of Poneloya hotels is the Hotel and Restaurant Posada del Poneloya. For $20 a night you can get a single room with private bathroom. The Hotel , though not located near the ocean, is a short walk away from the beach.
For an even more budget option, try the Surfing Turtle Lodge. Although situated in a remote location (2km away from Poneloya), this lodge is a perfect place to enjoy the beauty of the island, while getting a surpringly good service and comfortable rooms for a budget price ($10 a night).