How to calculate accurate usage cost for a longer contractual period?

[gyorgyjelinek]

Hi Experts!

I work on providing and accurate total cost (in DBU and USD as well) calculation for my team for the whole ongoing contractual period. I'v checked the following four options:

1. Account console: Manage account - Usage - Consumption (Legacy): this dashboard covers only the latest 1 year.
2. Account console: Manage account - Usage - Consumption: this dashboard covers a longer period, but the first 2 months are still missing.
3. Checking table system.biling.usage: this one is a main datasource for the previous consumption dashboard, but I tried to query it without joining anything for finding the missing 2 months usage - but no success.
4. Last option I am going to check is the REST API for billable usage logs. https://docs.databricks.com/api/account/billableusage/download But this option seems to be a quite large task based on this documentation: https://docs.databricks.com/en/admin/account-settings/billable-usage-delivery.html#high-level-flow

Is it worth to spend a couple of more hours with option 4. and build an application for retrieving and processing the logs - is there a good chance to find the older usage logs here?

Is there any other method worth a try?