Originally Posted by fastair

Shipments usiong dry ice are not cheap ($175 per container) and need to be packed in such a way as to allow the sublimated CO2 to vent. It will require addl checkin time as well as it will need to be inspected and labeled. http://www.united.com/page/article/0,6722,52830,00.html

At 50 lbs/each, I am pretty sure a deep freeze would hold for a very long time (ever try to defrost a big cut of meat in an inclosed insulated box, if so, you realize you won't be cooking it any time soon!)