Why is something that should be a library over an ORM or other data store now a service product?
From past experiences, on a reasonably big company (>100 engineers) that needs to do these money movements checks, it would save at least 3 engineers from support/evolution and not counting the development time for a good ledger.
On the cost side, the goal is to charge on average 1/10 of what you currently spend, so cost is actually a feature. I'm working on a self-hosted version for some customers that are asking for it, but not due to reliability of HTTP over the internet, I would love to hear more about this. Can we chat?