Amazon offers downloads of Saints Row: The Third: The Full Package for Windows for $5. That's tied with our May mention and the lowest price we could find by $8. It includes Saints Row: The Third, all three downloadable mission packs, and more than 30 bonus DLC items.
Also available are downloads of Saints Row IV: Game of the Century National Treasure Edition for Windows for $5. That's the lowest price we could find by $13.