I've been getting curious about forgeworld products lately. Always looked at their site, but never really got anything besides upgrade parts for something. Now, I'm looking at a lot of the units they have. Particularly, Necrons. My question is, I know you have to have IA 12 to use the units they sell. Is it worth it? Right now I have GK, DA, CSM, and Nec armies that I'm working on. Does all 4 have a place in IA that would make it useful for me to get or would I be stuck buying a book to just use one cool unit for one army?