what is this "Now" for mobile? Is it much cheaper ($25/month for unlimited?) it is under xfinity.com/now/mobile

my grandfathered cheaper xfinity mobile's $12/GB By_The_Gig  is gone, I am looking for some cheaper data plan. I see this new comcast's NOW service https://www.xfinity.com/now/mobile  when I tried to login, it says I don't have the service. How do I sign up and where to find the list of plan prices (I only see $25/month for unlimited)?