How many diamonds would you pay for this?

I have set up a trial chamber in my realm. You get 5 Ominous keys, and 12 Trial chamber keys. You leasurely walk around safely and use the keys to open all the boxes with zero risk. You keep all loot from the boxes, picture shown is an example of possible loot.

How many diamonds would you pay for this service? I have no idea what a fair price would be for people on my realm.