Big freezer bags inside of Styrofoam boxes worked for me, half water half air in the bag. I took my rics with me when i moved from chicago to costa rica this way. They were in the bags for 9 hours and everything way ok.
I saw an article a while back for these sort of "frag tubes" also. They were cylinder acrylic tubes meant to hold the frags in place and were used for shipping sps. I have no idea where to get them though