The easier way costs $0.05 cents per page. Imagine sending an invoice to your customer and the invoice itself costs 5 cents per page! That's prohibitively expensive for many applications. I wouldn't consider any solution that costs more than 1 cent per page.

We bill per document, so the number of pages wouldn't impact the pricing. A 5 pages invoice would come at 1 cent per page. However, it seems that each and every company has different needs and the pricing may or may not make sense for them. There are alternative billing options that we are considering but we want to keep it easy to grasp rather than go into billing kilobytes or ms of execution. We would be more than happy to discuss use cases and see what can work for each company :)

Some/most of these problems can be solved by using pagedjs and something like https://github.com/zipreport/zipreport-server