Rockstar Games confirmed that Grand Theft Auto V's multiplayer mode, GTA Online, will support microtransactions. Just days ago a file posted by '1880', a Reddit user caught everyone's attention. He learned that the store section of your console's pause menu requests a certain file found on Rockstar's servers. This file mentions special editions (such as the Atomic Blimp), but also what they call "cash cards". These cards range from $100,000 to $1,250,000.
Players will have the option to purchase these cash cards to upgrade their in-game bank statements. Rockstar assures us that we do not have to purchase these cards, saying "There is no in-game paywall and nothing that should disrupt the balance of the game. You don’t have to spend real money to attain the cars, guns, clothes, flash, and style of a high-roller in Los Santos, but can if you wish to get them a little quicker".
GTA Online economy is separate from single player mode as such you cannot transfer cash between the two. You will also accumulate money "much faster" online than you will playing the main game.
Looks like '1880' hit the nail on the head. GTA Online is included with the purchase of Grand Theft Auto V and will launch on October 1, 2013.