This is not as cheap as the downtown hotels you mentioned, but you would hit between your $50-$100 mark. Caribbean Villas Hotel is a 15-ish minute walk to town from its south of town location. Quiet at CV, but close enough for fun and party when you want; all rooms & suites have AC. They have a summer special where every night you stay after the 5th night is 1/2 price. They have rooms around $65 so the special would drop that per night average lower. Only 10 rooms/suites on 3 acres of land with wooded bird sanctuary, gardens, hammocks, free bikes and 300+ foot pier with swimming/snorkeling area. Great staff. You'll enjoy the island, I'm sure, wherever you stay.