Amazon is having a huge PC game sale through October 1st.
http://www.amazon.com/gp/feature.html/ref=pe_59010_16936220_pe_t4/?docId=1000598901
Some of the better deals include:
Borderlands for $9.99
Starcraft Battle Chest for $9.99
Civilization IV: Complete for $19.99
KOTOR 2 for $12.99
and...