You're right -- that IS way too much for cable internet.
Since you're in Nashville (which is close to my hometown), you have a couple of other options:
- AT&T DSL (using your traditional phone line)
- AT&T U-verse (if available where you live) - it's very similar to what you get from Comcast
Also, if you're just a casual user (checking e-mail, light web surfing), you might consider getting a prepaid USB aircard from Virgin Mobile -- I believe they're charging around $35 a month...