Yeah, I’ve got a spreadsheet for the total rewards, but I didn’t know what number to plug in for gold per gold key. @Mithran pointed me to @Shimrra’s data: 2.1 Preview - Guilds - #525 by Shimrra - your 17 is pretty close to his 16.93.
I agree that the keys basically pay for themselves before even counting the troops, traitstones, glory, souls, and gems. Clearly a great deal!