The Humble Bundle is known for alloying people to pay whatever price they want for video games. Their latest sale is called the Humble 2K Bundle which will offer select 2K titles for a deep discount.
For any price you will get BioShock, The Darkness II and The Bureau: XCOM Declassified. Pay more than $6.49 and you’ll unlock BioShock 2, Spec Ops: The Line and Mafia II. If you pay more than $20 you’ll get BioShock Infinite and XCOM: Enemy Unknown.
This sale will continue until July 22. To take advantage of it while it lasts, make sure to follow this link. These games will run on PC, Mac and Linux.