The best way I have found to transport live rock is to either get home brew bins if its fairly local, this allows you to hold a fair bit of water as well (assuming buyer will let you have some ). Failing that a good courier service and polystyrene boxes should suffice on a overnight delivery. However if picking this method please check the overnight temperatures this time of year as the courier service isnt likely to give a castlemain XXXX about its contents desipte requests.