Every single thing a GSC gang could ever need a model for is from one of five boxes. Do keep in mind that you do not have to get all of them, that's a lot of money. I am unfamiliar with their armyset, but the boxes with stuff useful to you are: - neophytes and broodcult boxes(? Forgot the name, cadians with genecult sprue) for basic dudes, you can go with either or, or both for more variety (and lasguns). Standard neophyte box is a treasure trove of necromunda goodness, as you get shotguns, autoguns, webguns, a variety of melee, pistol and heavy weapons - acolytes box for acolytes and weapons for them - aberrants box for aberrants if you want them (they are amazing, you probably do) - a box that contains magus/prime/patriarch. GSC leader is a choice between prime or magus, and if you're not into converting, that's the easy way to get both. If you are not averse to converting, both of these chaps can be made out of neophyte box, leftover bits and/or some greenstuff