Mexico is actually a value destination in comparison to other popular Carib destinations, especially for Americans. The peso is still hovering ~$21:1 which makes staying or living here quite affordable. Obviously prices in high season are much higher than the off season. But you can find very affordable accommodations if that is your primary goal, even in the Cancun hotel zone, if you do your research. Cancun is THE tourist destination of the Yucatán Peninsula, of course - it was created specifically for tourism - so you do have to do more homework to find the accommodations that suit your taste and wallet. I mentioned the RM simply because there are so many more resort-type properties, as compared to the more typical “grand hotel” experience that Cancun offers.

Tours and excursions are also relatively inexpensive, and again it’s very easy to compare reviews and pricing via Google, etc. Do you have any local TA’s that specialize in Cancun/Riviera Maya? And the most popular Cancun travel forum is on TripAdvisor, I would pose this question there if you haven’t already? Very active site but a couple of the destination experts are helpful, and many frequent visitors offer help as well...