Dave: It's lame to charge for weblog software based on how many weblogs you make and how many authors there are. A weblog isn't that big a deal. Manila lets you make as many weblogs as you want with as many authors as you want. Today's modern $2K computer can manage thousands of weblogs. Charge a fair price and don't fuss over how many blogs they make or how many people edit them.

I my experience the most significant cost when hosting any kind of web site or providing hosting software is support. And from a support POV charging per site/per user makes probably some sense (the more users, the more support - a server with 1000 users will trigger more support requests than a server with 1 user).

Providing a decent support is *the* challange for small companies willing to grow as we have seen in many cases. If you're not willing to provide customers' support, then charging per user per blog is evil ;-).