I'm guessing you are asking about ADO Shuttle Services? They offer vans and bus shuttle transportation in Mexico. 36 pesos is under $4.00 USD.
ADO (Ah-dthey-oh) is the major bus line in Mexico. In Cancun, from the downtown bus terminal you can get to nearly any major city in Mexico on the ADO line. It is the best of the major bus lines, the others here being Oriente and Mayab. ADO also has "premium" service called ADO GL, but the basic ADO is much better than Greyhound. You can also catch the ADO at the airport to the downtown bus terminal and to the terminal in Playa del Carmen. And you can return to the airport from both terminals as well. $36 pesos at the current bank exchange rate of $10.65 is a whopping $3.38 US.
