Hi, I'd agree with the others who said that there are several resorts in the Cancun/Riviera Maya region where you could meet that budget.
If you're interested in looking into those, you could start by glancing at the great Riviera Maya map posted as a sticky in the RM forum.
http://bestdestinationwedding.com/fo...era-maya-2278/
It was a helpful starting place for us, especially since it rates hotels as "moderate," "superior," "deluxe," etc.