I've done research to Science Diet, and found they have a sales representative for Central America. Costa Rico gets some. Unfortunately I have left tons of messages, and never gotten a call back by this guy.
The story with the other food is the typical "monopoly" game. Everything here is Purina and Pampered Paws and SanCas gets theirs from a farm store on the mainland. When I talk to them they just say that they order what they order. So its Pedigree, Beneful, Proplan, and that's it. It's even worse for cats.