Add-on quantities?

[compsci]

I am evaluating WHMCS to replace Optigold ISP and so far it does everything I need except for one detail. I offer spam filtering to my customers. It is billed per user monthly, quarterly, etc, to match the hosting account billing cycle. What's the best way to achieve this in WHMCS? In Optigold I would just add "Spam filtering - monthly" to an account and change the quantity to match the number of users.

[Matt]

You would need to use a configurable option on the product.

 

Matt

[compsci]

Do I have to create a configurable option for each possible quantity? Each domain is likely to have an odd number of accounts.

 

It also looks like I can do it with the add-on feature and manually calculate unit price x quantity for each order, but I don't think this will won't work if I allow customers to do self sign-up.