...less your dogs require a prescription diet or very special brand, I'd just buy dogfood here (and save your luggage space for items you CAN'T get here.) Pedigree kibble (50 lbs bags) and cans are readily available. Our dogs made the switch from Nutro to Pedigree w/ out much fuss. You can also talk to the folks at one of the bigger markets (Island Supermarket for example) who are usually more than happy to special order something... might take a couple weeks to arrive, but if you're getting 50lbs at a time, unless your dogs eat a LOT, it should not be a problem.
Many of the stores will give you a discount too, if you buy by the case (if you're getting cans.)