Okay, it's a little bit of work, but worth it.
Bohemia have a 50% off sale, but another website is giving away a 30% voucher code for Bohemia as well, so you sign up to a website to get the code and then go buy the game from Bohemia at 50% off and apply the 30% off voucher.
Better explained here with links. (http://www.hotukdeals.com/deals/arma-3-12-50-bohemia-store-w-code-1988522)
That's a bargain for a amazing game