We have an existing subscription to Supermetrics add on for Google Sheets - but we'd like to add-on an additional user. 1) is this possible and 2) if so, what is the cost?
At this time, is is not possible to add additional users to Google Sheets licenses. They only support one user ID at a time so you need to either purchase additional licenses for additional users (we do offer bulk discounts) or share credentials for a single account so that others can log in as that user to access the license.
We also don't have enterprise bundles at this time - we hope to change this in the near future, but right now you have to purchase each tool separately. We do offer multi-product discount of 20% if you have both Sheets and Data Studio licenses, for example.