Some of Comcast's promotions do have a contract/early cancellation fee. Particularly if it's one of those which offer a rebate gift card for signing up.
Your best bet is to call them up directly, and ask for any plans which do not have any contract terms or early cancellation fees, and see what they give you for pricing.
In my area, I can get (if I were a new customer) "internet plus" service which offers 25Mbps down/5Mbps up, and basic local cable TV for $50 a month, no contract, no cancellation fees. For $60, they offer the same terms but with 100Mbps down/10Mbps up (they call this the "Blast" tier).
FWIW: I'm on the blast tier, and Comcast consistently exceeds their advertised speed. I'm not at home so I can't do a speedtest until tonight, but here's my most recent one:
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There is one caveat: Comcast's customer service
is pretty lousy. For that reason, I can't say they're the best, or even very good, and my rating of them is pretty much "meh." But, it can't be any worse than CenturyLink, and the service itself has been reliable enough for me that the last time I had to call customer service for assistance was when Hurricane Sandy knocked down our line. So that's a bag of hurt I've not had to deal with much. If you decide to go this route, you probably won't have to deal with them either once you're installed, until the time comes for you to cancel.