Look for the following in the terms and conditions: "Equipment fees not included. Installation fees may apply."
I'm a former COX customer and when I first signed up they charged me for installation and the cable modem. I called in to complain and got them removed. But when the modem failed I had to buy the replacement.
If you go with COX read everything carefully. Don't go by what an agent tells you, that may not be the whole truth. Price their service online and see what is included without clicking the "buy" button. Make sure that ALL of the equipment you want and the installation is listed.