Americans will spend more than $1.6 billion in 2010 on virtual goods and social gaming, according to Target, citing a figure from Inside Network.
Users who play FarmVille are prompted to buy a wad of currency, up to $50 worth, the first time they sign up. As they work at raising a virtual farm, they can buy items such as seeds, fuel, buildings and decorations for the buildings. Signing up for the games is free.
Users pay for items with FarmVille coins, a currency with an exchange rate of $5 for every 7,500 coins. They pay for the currency by major credit card or via PayPal.
Items on FarmVille can be pricy. One of the more expensive ones, a Villa, goes for a reported $600.
Facebook allows third-party developers to host such games on its site.