how do i make it so that people can exchange diamonds for money using and admin/npc shop. I tried making an npc shop but i still own it which means that the money will still come from me. I get the message "the owner doesnt have enough money fo you to buy from this shop". Is there any way to get this to work how i want it?

Use /shoppy npc_shop <x> <y> <z> where x. y and z are the coordinates of the block <3

You need operator to do this, but that should be a given