Well, the good news is that you don't necessarily need a static IP address.
This Web site tells you all about setting up a Web server using a dynamic IP address.
If performance isn't an issue, then you can probably just stay with your current cable provider. Your address will be kind of ugly (something like
http://www.example.com:8080), but you can mask that. Just make sure you're not violating any TOSes by serving content.
