bioshock 1 amazon?

[Eamon Burns 99]

http://www.amazon.co.uk/Take-2-Bioshock-PC-DVD/dp/B000V1VZNE/ref=sr_1_1?ie=UTF8&qid=1382631509&sr=8-1&keywords=bioshock+pc
why is it so cheap here and on steam its£13?

 

[Metalrenok]

Sales, my friend..sales

 

[wanderer11]

Steam isn't always the cheapest place. I always check amazon and greenmangaming before I buy on Steam.