Buying and selling FIFA 15 coins contract relies mostly on luck. You need to determine your price point because there are a number of variables that come into play here: profit margin, time, and consumable pile/transfer list size. You need to find a profit margin that makes you the most amount of money. While you can try to sell at 100 coins more than you bought at, it may be difficult to keep up for long enough to make it noticeably profitable because your available space for these cards will keep filling up.
