Commanders and Comrades! Steam are offering, for a limited time, the Tiberium Wars, Kane's Wrath, Red Alert 3 and Tiberian Twilight titles at the knock down price of 3,39€. The offer ends on February 12th, so you'll need to hurry. The offers are linked below.
The titles (except C&C4: TT) are compatible with
C&C:Online, so if you're looking for an affordable way to get online in those games, this is probably it. N.B. You need the Steam version of Tiberium Wars to play the Steam version of Kane's Wrath.