This line is exactly why ISPs should be treated as a utility and not be allowed to deny service to anyone except in special circumstances. Many people depend on the internet for their livelihoods (like me!) and denying them access at their home is almost akin to an electric company denying someone access to the grid.
Call them and ask! They may punt you to one of their customers if you just want a U or 2.
If you plan on your own AS and IP space - full network independence - ask which carriers are there, and plan on a quarter or half rack for a router. You'd also need to become a member of your regional Internet registry (e.g. ARIN in the US) and ask them for resources - e.g. IP space and an AS number.
