Nah, let's just kill him right away
Iconomy is dangerous as I have tried this in my private server. You have to configure it perfectly for no loopholes to appear. For one, I used essentials Iconomy and I bought gunpowder and sand, made TNT and sold that to get almost twice the money back and redo the proces over and over again.
The system would also have to be like shops in RL, meaning you would have to gather diamonds, then give those to your shop so people can buy it. At least that rules out the loophole I explained above...
It still makes the game alot different and I guess we won't have it cause Zerg already said no to Towny, which is Iconomy based.
Messy post, but, whatever