WAW is like $30 on Steam, but probably cheaper elsewhere.
I have SGTW2, but I dont have time for an MP campaign right now.
Ventrilo is up at www.80hd.net, Praetorian and his pal have the game and will definitely be up for a co-op campaign.
I might do like head to head sometime if you want to do that, Pra3 might too.