AC-130 H's and U's are way good CAS platforms, however, they are so specialized and thus expensive to own/operate that your money would probably be better spent on more conventional CAS platforms. Add in their vulnerability to SAMs (lost one in GW1 to a SA-7), and it really becomes something to think about before buying them.
That said, they are freakin' awesome!
Loved the BBMF Lanc outfitted with side guns idea listed above!