I looked into these very briefly, so if someone knows more, feel free to correct me.
The cameras and cell units themselves will run you a couple hundred dollars. Moultrie makes a cell system that an be used with several of their higher model cameras, all which have very good battery life on their own. I'm not sure if the cell unit has its own power source or if it shares the batteries from the camera.
The tricky part in this whole ordeal is finding an area with high deer traffic that still can send and receive cell signal. Also, you are going to be hit with monthly service fees, pay per picture (which can get frustrating if you're camera falls, catches 500 pictures of the sun rising or setting, or if you find out the camera is set at a bad angle), and/or stuck in a contract that does you no good between February and August. I was seriously considering one of these until I found all of this out. Do your research and ask more than enough questions!!