What's your budget?

There is a cheap hostel/posada close to the bus terminal. I think you will find more information on the Lonely Planet forum. I've never investigated that one.

There are a few cheap hotels (200 to 300 pesos) if you walk along the avenue going away from the beach.

When you come out of the bus terminal, turn left and walk along the main street. There are several hotels in the US$50 to $100 range. Here's one I looked at, but didn't stay in:
http://www.mayabric.com/

Some of the hotels on the main street are hard to see because there's just an small entrance on the street, and the hotel is behind the stores.

If you come in low season, it might pay to negotiate.