Hello,
You can try using the Multiple Players feature in Reports to select all players, then add a filter according to the buy-in, and export all the hands:
After that, simply import them into a separate database.
This way, each database will contain only the hands for a specific buy-in, allowing you to compute reports for that particular buy-in in the Statistics section.
However, please note that exporting a large number of hands may take a significant amount of time.