With out using user manager, I want to know if there is a way to redirect unpaid users to a page informing them they have been disconnected until they call in to make a payment.

I've thought of making a specific profile that will add an incomming and outgoing packet mark and then redirect based on that, but I can't figure out how to do this. Any suggestions?

The easiest way to do it will be to create the NAT rule to redirect them to the web proxy and use an address list with it. That's pretty easy to accomplish. FYI, you may also want to create another rule(s), using the same address list, which drops other types of traffic or all traffic since the NAT rule will only redirect port 80 traffic. You will have limited success with port 443, so I would just drop that traffic.