I'm sure you can get ice at any grocery or convenience store. There's a store in Dinosaur that we call the "Dino Eddy". People running shuttles always seem to stop there to get more snacks, drinks, gas, etc. I'm sure there's ice.
A great thing I've done in the past is to make ice actually in your cools. It's a little bit involved and you need to know someone with a walk-in freezer (like a restaurant). The best thing to do is put about an inch or two in your cooler every day until you have 6 - 8 inches. If you put all the water in at once you'll get a big bulge of ice. The ice lasts a long time so it's great for long trips. On my first Grand we had ice until the end and it was in August.