You may be able to view a product line price sheet at https://www.xfinity.com/support/rate-card/. You should be able to pick up a price sheet as well as a channel lineup at a Service Center or Xfinity Store (check locations and hours at http://www.xfinity.com/support/service-center-locations/), or have Customer Service send these to you.
Also check the web site, customer service, and this forum for special deals not listed on the price sheet.
Product line pricing may have been included with one of your recent bills. Check https://customer.xfinity.com/.