Yeah, selling coins is worse than buying coins... You get 2 strikes on buying. First offense selling gets you banned. Frankly, I don't believe you are going to be tricky or deceptive enough to sell enough value in coins to afford to buy another version of the game before you get banned. The only way you profit is if you sell enough to buy a new account before you get caught and permabanned. And eventually they can ban your IP address if they figure you out.
Do what you want, but I thought it was worthwhile to warn you...