GamersGate is currently having an 80% off sale for AI War and all its DLCs; the entire pack is only $3.30 USD, whereas individual DLCs are at $1.00 (Neinzul is $0.40). Cheapest it has been for a long while, so be sure to seize it before it ends in 16 hours. All keys are compatible with Steam.
The Winter 2013 AI War Sortie Bulletin topic at the community hub is a place to find other players.