The standard cost of the Multiple Immigration Form (FMM) necessary to do tourism in Mexico (specifically, FM2) amounts to 500,000 Mexican pesos since January 2017. If you travel By plane, the cost of the FMM is included in your ticket. You have all the information in: «The FMM to travel to Mexico: what it is, where to get it and how to pay for it«.
You have all the information in: "The FMM to travel to Mexico: what it is, where to get it and how to pay for it".