We've seen Irrational Games' BioShock at a $4.99 price point before, but I'm not sure that we've ever been able to pick up both games - including a BioShock 2 four-pack - for 75% off their normal price. If some cheap mid-week Rapture action sounds like a good thing to you, head over to Steam's promotion page within the next 24 hours to grab one or both.