There are two ways to turn your Lego minifigs into Ghostbusters. Well, three, if you count using your imagination. Pfft. Imagination if for kids and suckers!
No, what you want to do is either buy unofficial third-party Lego equipment or do like this guy, and make decal/stickers to apply to the minifig bodies. Anybody with a little photoshop talent could do this themselves, but hey, if someone has already done the heavy lifting, $6 is a steal!
Lego actually does both – spacemen have cool spacesuit decals on the front, but air tank equipment on the back, not a flat sticker like the proton packs shown here (as awesome as they are). So, I guess I’m arguing, buy a sheet of these decals as well as the GB Lego equipment, and put the two together!
Thanks to Rodger for the link!