I do not know what you are planning on doing but to have an antelope cut up in Casper will cost about $100. If like everyone else, you want it done and ready to go in three days they add $20. To give it away to charity it must be butchered by a licensed butcher so it costs $100 to give to charity.
What I do that works well enough is to use the big six day extreme coolers and butcher and bag my antelope and then buy about 20 pounds of dry ice. That is enough to freeze the meat fairly well and then it will stay frozen in the cooler for quite a few days. You can add regular ice and dry ice as needed. The trick to it all is to have the extreme coolers and to butcher the meat into small packages so it freezes easily.