Yeah, DayZ is the main reason I've even thought about getting the game. Arma 2 could drop in price next year or whenever Arma 3 comes out, but for now I haven't seen much of a price drop. I wasn't keeping my eyes glued on the price though.
https://store.bistudio.com/arma2-combined-operations-steam-version
Everything is 25% off on the Bistudio website, but I figure that Arma 2 would be the most popular. I haven't even heard of any of the other games, but here is the link if you are interested:
https://store.bistudio.com/
I went to my local gamestop and the refurbished unit they had was $79.99(the online price).
I bought it because it looked like brand new, and thankfully it is working great. Even at $79.99 it is still a great deal!