We have cable based internet. It's not cheap, but it's cheaper with cable than without. In fact, the difference is more than the lowest tier of cable, which is pretty much just the local networks, plus CSPAN, Weather, WGN, and the shopping networks. We pay approximately $13 for the cable portion, which gets us internet for about $16 cheaper.
All that is not the badassity part. About 2 years ago our cable company (it's the biggest and most hated) sent us a tiny box in the mail and told us we needed said box to keep viewing cable. It was a lie. The cable companies are required to send you the high definition signals from your local affiliates at no charge. When we plugged in this little box, you could no longer get the stations in HD, just the crappy LD signal. Conveniently, they moved all the stations around at the same time so it seemed like you didn't get them any more. We took out the box and did a scan on our television and voilą, all the HD network channels are still there. They even still move them around every so often so that you have to rescan.
Here's another nifty benefit we get. Almost all cable networks stream their video. ESPN, Turner, USA, etc. None of those are included in our package, but a couple years ago we upped our package for the Tour de France and Olympics. We lowered it again after the Olympics ended, but ever since, when we log into the cable network websites with our cable TV email, they recognize our account and we can stream. This is particularly nice for ESPN and other sports stations, as those would be the only reason we would expand our cable (my wife is actually the bigger fan).
So in summary, the very lowest tier of cable comes with HD versions of the major networks, and if you bump up your cable and drop it down again, you may be able to stream networks that were in the upgraded cable. All for a cable price of about $13. The downside is that the internet is over $50, which puts us at $72 all in with taxes, etc.