The choices from TWC is the $11 a month cable box (no DVR) or $21 a month for the DVR. Each TV needs one.....
You can build a HTPC (I am currently running one), where you use a cable card tuner to display on the TV. Costs are a Windows 7/8 PC with Windows Media Center, and a cable card tuner ($100 - $200).
Other options are a TiVO box (about $200) plus the programming fee.....the only difference basically is you own the equipment as far as costs for TiVO - I believe their programming fee is about $10 per month.
With the TiVO of HTPC - you will need a SDV converter to tune the stations....TWC supplies this for free.