Trade-O-Mat

Sells whatever its owner sets up: “Wants” is the price (iridium coins, for example) and “Gives” what it sells, with their amounts. Anyone puts the payment in the input and gets the goods in the output. Goods come from an adjacent inventory (a chest, or better a Personal Safe of the same owner, which nobody can empty) and the payment is stored there. It cannot be broken; the owner removes it with a wrench.