for the most part cable IPs change very infrequently. You could if you are gone for long trips use DynDNS which if you get a simple free web address from someplace like dot.tk you can have DynDNS update you're dns ip entry automatically so instead of using your ip you would use the domain name address to access the cameras

The most direct route to getting a static IP is through your ISP provider, as you know. It's up to them to offer products and services the deem viable, regardless of whether it matches what we consumers actually want. If what local providers aren't offering what you're looking for there may be another alternative available to you. Doing some searches along the lines of "static IP services" will result in finding providers that work along with your local service (read "additional cost!"), that can essentially mimic a static IP for you. Although I've never needed my own static IP address I have friends who have done this and been quite happy with the arrangement.