I've pondered variations of this many times. If you ignore complexity some truly fascinating formulas can be had. You can for example create tons of value out o

I've pondered variations of this many times. If you ignore complexity some truly fascinating formulas can be had. You can for example create tons of value out of thin air by having traders express an interest in items if they are sold below x. A baseball card could have an infinite number of partial owners and automatically change "hands". Some just want to trade them and are not interested in physically holding onto them (if not worried) while others just want to stick the postal stamps in books and show off. If you are for whatever reason unable to send it to the new 51% owner on his request you automatically refund the entire item at market value.