It looks as if paying in pesos and using a credit card for a foreign tourist is a close to a wash. Dollar blue seems to be @ 20 % above official rate. That being said , the hotels are always 3-6% higher on their " official " exchange rate. This has been discussed on another thread. If you can get a good blue rate , cash may work the best but may not be worth the effort. I always make the mistake of going home with to many worthless pesos. Have 100k worth from a good session at the casino. Should have converted them before I left and things went south.