I found this for October 5-9, using hotelscombined.com and then clicking the hotel-board.com link. Also available for a little bit more through Skoosh. It may be available for other dates (for example, I just checked October 10-12, and it is then too). This is for a single, but prices are a little higher for a double.

This may not seem like a terrific deal, but it's 1/3 of the website price, and SMA is an expensive Mexican town. The hotel has good reviews.

I just wish I could get this price in the Christmas/New Year period!