What is the cheapest Internet provider?

I am paying $80 for my Internet service a month. My ISP is trying to get me to hook to cable again, so that I get a bundle plan that includes Internet to reduce my monthly bill. I am not sure I want cable again, but I am paying a few dollars short of what the cable plan would cover just for Internet. So, maybe I should take their offer? Do you know of any Internet plan that is cheaper?
Thanks for your help.