Invoicing or billing system?

[MySpaceFTP]

I'm looking for a way for customers to add products to there account, and pay for them all at once at the end of a billing cycle. Sort of like e-bays billing system for there sellers.

Let me explain a little better......
I have a section of my site that i want people to pay for each time they use it (an online service, $2 per use). I want it to add the $2 to there account each time they use it and at the end of there billing cycle, i can e-mail them an invoice with a checkout button or link where they can pay there bill. Is there any portal system or script out there that can do this?

Thanks in advance for the help!

[etechsupport]

What billing software you're using so far?

[MySpaceFTP]

Currently it's a free. But i want to start charging for it. I set it up for free to build up a client base, and now that i have that, i want to start making money off of it.

This is the way I would need it to work:
Customers visit my site and log into there account
They choose the service they would like to use
A $2 charge is added to there account
They are then taken to the page where they can use the service they selected
At the end of there billing cycle, there credit card that is on file in there account information is automatically billed for the previous months total. (Through authorize.net)

In the backend section, I would need to be able to view all customer accounts, there account information, previous (paid or unpaid) invoices, and there current (open) invoice. (As well as being able to add, remove, or suspend accounts)

This does not have to be in any special design or style. I just need a crude setup. I will be able to integrate it into my site. I’m just not as advanced in my programming skills as all of you are.

Is there any kind of script or CMS that anyone knows of that would work this way? Or one i can modify to work this way?