Hey there, DragonHeadJon
Welcome to the Microsoft Community forums
This is high in price, mainly because it is a Backwards Compatible Game on the Xbox One. Thus meaning people are still playing the game even now. Also, this is the latest Call of Duty Franchise on Xbox 360 - well proper game anyway, Black Ops 3 is only a Multiplayer game on 360 with no campaign.
BossDweeb is correct. All Microsoft do is sell the game through the store. They have no control over the prices, as this solely lies with the publisher and developer.
Regards,