In the game Maplestory, players can earn a virtual currency called a 'meso'. This currency is used to either buy items from NPC(Non-Player-Character) merchants or trading with other players. You can earn mesos by killing monsters or selling your items.
Mesos can come in various forms including the most basic and cheap brown coin, then the gold coin, next a bundle of cash, and then a sack of gold.
http://www.mapletip.com/forums/style_emoticons/orange_mushrooms/coin.gif Gold Coin - 50+ Mesos
http://www.mapletip.com/forums/style_emoticons/orange_mushrooms/cash.gif Bundle of Cash - 100+ Mesos
http://www.mapletip.com/forums/style_emoticons/orange_mushrooms/sack.gif Sack of Gold - 1000+ Mesos