Bethesda is running a sale on Fallout games on the Humble Store. You can get games like the original Fallout, Fallout 2, and Fallout New Vegas for $4.99, Fallout 3 Game of the Year Edition for $11.99, and Fallout 4 for $14.99. They also have sales running on Fallout DLC, including Fallout 4: Season Pass.
Source: N4G PC Fallout games are on sale at the Humble Store