I think you can buy them, for a steep price as usual, from Matrix Games. At least some of them.
http://matrixgames.com/products/335/details/Close.Combat.-.Cross.of.Iron
That said, I've head that the Combat Mission games are quite similar. But I've not played them. You can get them at GamersGate.
Otherwise you should try Men of War. Those games are bloody great. Those are availabe at Steam and GamersGate and probably elsewhere. Hilariously bad voice acting though.