I just use the heat packs you get at WalMart. The ones you just smash to activate. Just bag the coral in a plastic bag, place it in a small thermos ($2.00 at Walmart), and place in a styrofoam lined box. Place a few heat packs in the box and th temp. should be okay.
I recieved some SPS that had been in 60 degree water overnight and they survived....