The cheapest 2K game right now is X-COM: UFO Defense at A$0.49 (Eneba), of the 153 we compare.
Right now we have in-stock offers for 2K games from Eneba, G2A, GGPick, Gamivo, HRK Game, Instant Gaming, K4G, Kinguin, Steam and YuPlay.
Not always. Stores that sell their own keys, such as Steam and GOG, add no service fee, though sales tax is added at checkout in the US and Canada. Marketplaces add a service fee at checkout, and some payment methods add their own, so on a marketplace the total at checkout will be higher than the price listed here.