How is my idea?

By paying coins, you enter a challenge ( or event or something like that)...where you get vouchers along with coins if you are able to sell any of the products of a specified production building to your roadside shop at maximum price within a given time.Off course this doesn't apply to things like upgrading and expansion materials. It happens like this: You click a building (say juice maker) and there is a button to start the challenge for a specified time. Now within that time if you send any of the goods at maximum price, you will get voucher along with the coins....