Roblox: Understanding Profit & Loss

Owen and Anya love to play Roblox.  The game allows them to develop their own games.  In addition, they are able to buy virtual items such as hats and hair using a virtual currency called Roblux.  Some items that are sold become rare and limited items and if bought at the right price can be resold at high profits.  The kids regularly buy and trade limited items to earn Roblux which they can then use to buy other items or develop and market their own games.