I'm in Costa Rica and I just have a freight forwarder setup in Miami, I shop on Amazon, Ebay, etc no problems. The billing address of my CC is set to the same as my freight forwarder to make things a bit smoother.
The freight service is called Aerocasillas or Aeropost. (
http://www.aeropost.com/main.htm)I didn't see Mexico listed but you get the idea.
I have found that the dealer in Miami doesn't carry a lot of stuff in stock and keeps having to order from the Hobie factory in California which causes delays in the order. I would instead purchase from a dealer as close to the factory as possible and ship via UPS ground or something of that sort.