There are a variety of places to stay right in town depending on your budget.
You can look these all up online.
2 budget places with bunks of private rooms available:
La Casona Real
Hotel Pepita is a good option for 39US per night (at the time of this writing, subject to change)
Suites Bahia is a hotel in an excellent location and the offer good deals for longer stays.
Mi Casa is a beautiful bed and breakfast for reasonable prices and also better deals for longer stays.
Be sure to check out Air bnb, many of our students use it. In low season (August- November) there is more available and you can see photographs of the available apartments.