Cash is king, not many shops and no street vendors accept credit cards.
There are lots of ATMs; charges vary between 20 and 82 pesos per transaction.
Ensure that you have 5 pesos for the lavatories
Lunch costs between 100 and 150 pesos without drinks
Dinner costs between 200 and 300 pesos
Tips are 10 percent of the cost
Haggle, you can generally reduce the price by between a quarter and a third of the asking price
Have someone in the group who speaks Spanish, thanks John
Lots of winding roads so take some travel sickness pills if required
Save your American dollars for Cancun