All "buy Now" items sell for gems only. My 6 offerings were 1fp-1 gem, 75 prev. era goods-11gems, 200% att. boost for att. army- 42 gems, 75 goods- 11 gems, 30m mass supply rush- 5 gems and 4 rogues-17 gems. Better stock up on those gems that they throw around. Coins for auctions only going forward