Mount and Blade Collection 75% sale on Steam:

http://store.steampowered.com/sub/8029/

It is also worth noting that they have updated Warband a couple of days ago. I have played only Warband myself and it is in my opinion the best video game that I have played to date. Along with multitude of features this game presents, it is the only game that I have seen where the world around you is alive and does not depend on you, and yet you have the option of changing it - a masterpiece in my view.