Cheapest i can find anywhere for this at the minute, im assuming it can be bought for this price through the console too.
£15 for 5 days onlyhttps://www.microsoft.com/en-GB/store/p/Tom-Clancys-Rainbow-Six-Siege/C12T09DSVP8J
Siege is also free to play this weekend on all platforms, so you can try before you buy.http://blog.ubi.com/rainbow-six-siege-play-free-weekend/
PC: To download the game for free on Uplay, please go here and follow the steps provided. A full list of PC hardware specifications is available here.Play free on PC from 1:00pm EST on February 2 until 4:00pm EST on February 5.
PLAYSTATION 4: Join the free weekend on your PlayStation 4 by visiting the Rainbow Six Siege product page on the PlayStation Network. PlayStation Plus membership is required to play online. Play free on PlayStation 4 from 1:00pm EST on February 2 until 1:00pm EST on February 6.
XBOX ONE: To join in on your Xbox One, visit the Rainbow Six Siege product page on the Xbox Store. An Xbox Live Gold membership is required to play online. Play free on Xbox One from 3:01am EST on February 2 until 2:59am EST on February 6.