Have them offline and copy the raw drive/tape to trusted 3rd party (as they must do regularly for backups anwyway) and have that 3rd party query the data. Or if the data is old enough, have them just copy the backup to the 3rd party.

This should eliminate any query expense they would have had (as it's been replaced by raw data copy expense.)

And the 3rd party is to protect the data you're not supposed to get.