Origin is EA's version of steam for their own games, free to install origin and make an account. They often have sales also. BF5 is coming soon, around October. There's a good chance both BF3 and 4 (BF4 if you prefer to fly jets as Gam3r01 says) will go on sale then if not cheap enough already. BF4 multiplayer would still be pretty active atm but may change with BF5.