The humble Store is having a Spring Sale from May 6th to the 21st, with many games on sale and daily flash sales with 80% to 90% off. The Humble Store supports charity with 10% of the proceeds. As of writing this, Mortal Kombat Komplete Edition, Final Fantasy VII and VIII are selling for $4.99, Hotline Miami at $2.49, Trine 2 Complete Story for $2.99. Fine these and many others on The Humble Store.
Source: Humble Store
Image: Humble Bundle