I just bought my Costco membership in Cabo San Lucas, Mexico for 450 pesos. That's about $36 USD (depending on the exchange rate). In the United States the Gold Star Membership at Costco is $55 USD. That's a savings of almost $20 USD!
I use my card in the United States and it is considered an "International Membership." It works the exact same as the Gold Star Membership. Sometimes I have to tell the associate that I have an international membership because they have to key a certain number before ringing up my items.
I use to pump gas at Costco and it works!
I am all about saving money especially when things can be cheaper in Mexico for the exact same thing in the United States!