I get mine from a friend who has chickens. I have one of those plastic containers that Walmart sells in the sporting goods department for carrying eggs. It's a bit heavy, but for shorter trips it's ok.

Another option is to put them into a saved carton. I find the paper ones work better than the styrofoam ones. Put that inside a ziplock (if it busts you don't want egg all over the inside of your pack), and then cushion it as best you can. If you're carrying extra clothes of any kind, even just a pair of socks, use that to help keep them from breaking. There's a knack to it, but it can be done. The good part about carrying them in the paper carton is that it can be burned or crushed and packed out when the eggs are gone. The good thing about the plastic carrier is that it can be reused over and over. The paper one can be, too, but it wears out much faster. So you get to choose which one suits you better.