I'm just back from the Hotel Zone in Cancun. City busses running the strip are now 8 1/2 pesos (about 70 cents, USD)... still quite a bargain. Be sure to pay with Mexican pesos; the drivers do make change within reason.

Taxi from the south end of the hotel zone to the airport was $25 USD. Probably could have negotiated cheaper if I'd lugged my bags to the street and hailed a cab on the road, rather than letting the bellhop summons one for me.

As stated elsewhere, taxis from the CUN airport to the hotels are a ripoff. Instead, take a shared shuttle that the various travel agencies offer. But first contact your resort and inquire with the concierge, as some resorts do offer their own shuttle; otherwise the concierge can usually book a shuttle for you. (Some require a double occupancy booking.)

Generally don't take a bus from the airport to your hotel (or vice versa) because busses go to downtown Cancun first, and then out to the hotel zone, which will end up being in excess of an hour journey, when it should only take 20 minutes max.