Sorry if this has been done already.

Once I have the animal skin (in Africa). What is the process/cost to get it back home? Assume a single large kudu, tanned, etc..

You leave instructions and contact information with your PH. You come home. At some point your trophies are delivered to the taxidermist. At some point they will do what you request, mount or just tan, or just dip and pack. They will contact you for payment. You pay them. The trophies then go to the shipper. The shipper contacts you. You pay them. You can use a customs brokerage to clear your shipment or you can do it yourself. I recommend you use a customs brokerage to assist you with all of this. As far as cost,
it varies
It is not unusual for this whole process to take a year or more. Be patient.
There is a lot of information on this forum regarding getting stuff home. Good luck.

Grady:
Please go to huntingtrophy.com The FAQ section has a run down of each process involved in getting your trophies back home.