Compatible Modem/Router

Now currently have a rented Xfinity Wireless Gateway - Technicolor CGM4140COM and Gigabit internet plan.

I would like to buy my own.

I went to the support section of my account and looked up Device Info - Xfinity to see what is compatible and there are only two with built in wi-fi routers - Arris G36 and Netgear CAX80. I cannot find the Arris G36 model for sale anywhere and the Netgear unit seems like overkill and is expensive at $429.