I have found a couple of sites to purchase Mexico Telcel Amigo sim cards in the U.S. prior to departure: www.cellularabroad.com and www.telestial.com (these also provide sim cards for other countries around the world). However, I am curious to know if sim cards are easy to purchase in Mexico, and if the prices are more competitive. Does anyone know if I would get a better deal if I just waited until I got to Mexico before purchasing a sim card, instead of buying one from a U.S. provider before departure? Thanks for your help.