If there was a third party solution that provided automatic bandwidth monitoring for hosts on a colocated or dedicated server network, along with automatic overage billing with full featured end user interface and administrative control panel for account setup would this be of value to anyone ? If so how much would companies pay for it ?

Basically all the Hosting company would need to do setup an MRTG server on there network and the remotely hosted Bandwidth App would do all the rest.

Any thoughts ?

We sort of do that for our ded/colo customers who offer web hosting. It's a web based management app that they can log in and check reports on banwidth usage by server.