sidney wrote:
[snip]
> another option I would like is to be able to pay their bill
> through a webpage.
>
[snip]
>
> I just need it for about 20-100 users.
PayPal is a good option for such a small number of users. A little bit of a pain to setup, and not quite as easy as going with a "normal" credit card service, but it is not all that bad and the price is right. With the small number of users, hand-holding through the account setup would not be that bad. Plus, once they have a PayPal account, subsequent payments are not much different than most other online payment methods.
PayPal also offers a subscription service, which auto-bills your customer's credit card periodically (monthly, etc.) for a FIXED amount. Probably would not apply in your case, as you will have a variable bill, but others might be interested.
Scott