Cheap & local: Los Colectivos
You can get from Playa Del Carmen to Tulum for only 35 pesos (3$) with a small van called a “colectivo” (take a look at it on the map).
Colectivos are everywhere in Mexico (and in many other countries of south & central America). They are the local (and cheap!) transportation that Mexicans use to get around and go to work.
Colectivos are small vans of 12 to 20 passengers and are very comfortable. The vans are managed by syndicalist groups, for which each driver pays a daily rental. And since more and more tourists now take the Colectivos, tourism has become quite an important economic contribution for the drivers & their syndicates.