2K Games has bundled 20 games together on Steam for the budget price of GBP 35.99.
Among them are BioShock, Civilization IV (plus expansions), Civilization III, Prey, Freedom Force and Sid Meier's Pirates!
We make the combined total of all 20 games sold separately GBP 141.71. Even buying Civilization IV plus expansions Warlords, Beyond the Sword and Colonization costs more than GBP 35.99.
If that doesn't sort you out for a weekend then nothing will.