I have to ask -- is the deer tallow in the Etsy soap from farm raised deer? If it's from wild deer harvested by legal game hunting or if the chain-of-ownership cannot prove the tallow was from farm raised deer, it may be illegal to sell this soap in the US.
There's been quite a fuss on a facebook tallow soaping group lately about this matter. Some soapers want to sell soap and other products that contain bear or deer tallow from legally hunted wild animals. The state Fish and Game departments are telling these soapers that it's illegal to make commercial use of the tallow. You can soap with this deer tallow to your heart's content ... you can give it away to friends and family ... but you can't legally sell the soap or make other commercial use of it.
The point of the law is to discourage poaching and over-harvesting. In the 1800s and early 1900s, there were no controls on hunting, and many animals -- bear, deer, elk, moose, otter, egrets, carrier pigeons, etc. -- were exterminated in many US states.