Lease Charter cableCARD, buy my own box?

You only have 2 options as far as cable cards go TiVo or HTPC. The TiVo option will require a subscription which can be a monthly fee or a fairly substantial one time fee for lifetime service.
The PC route will require some initial expense I've read about options as cheap as $65 but I'm sure this would require a lot of tech savvy shopping and self assembly but end result would be 2.00 cable card fee would be only recurring cost.
I DO WANT TO STRESS DON'T BUY A CABLE BOX FROM EBAY!!!! You will endup owning an expensive paperweight and will posably be involved in a criminal activity also.
I hope this helps.

.... or perhaps three options if you can get/find a Moxi

They will work. The trouble is no one (legitimate) is selling them. Also the Cable Co is not going to activate a probably stolen box.

HTPC can be made to work exactly like a cable box. Although it takes some effort to set up, in the end, you use a regular remote and the user experience is no different than a cable DVR. Beats paying $20/month or more, plus the interface is much, much nicer and storage is practically unlimited.

My HTPC is in another room and stays asleep whenever nothing is being watched or recorded. My interface is the XBox that was already connected to my tv and a regular IR remote (I use a universal). I paid about $100 for a cable card tuner to connect to my PC and $2/month for the card. It works very well and paid for itself in less than 6 months. I highly recommend it.

If you can wait a few more months, Ceton will begin selling a subscription free, cable card DVR called the "Q". It will be expensive, but won't have recurring fees like Tivo and won't be as complicated to set up as an HTPC.

I have a HDHR3 Prime on my network and a tiny PC connected to the main set. Most of my channels are copy freely so I just use the QuickTV app that came with it. Change channels from a list using a mouse. Even the Wife can do it...And she can watch TV while playing SCRABBLE.