@whitelet and I have a simple spreadsheet of the buffs we use and the coin & endeavor they cost. I expanded the spreadsheet to include all guild buffs.
1. The link is set to view only. To use the calculate function, copy or download the sheet to your google/local drive.
2. Put “1” into the cell next to the buffs & levels you want to run (Column F). The total cost will be shown in the upper-right corner.
3. Endeavor Member: each guild member/alt can generate 500 endeavors/week at max. Thus It tells you how many active members/alts your guild need to cover the endeavour cost.
4. You can delete the existing "1"s in the spreadsheet. Those are examples.