On the page for the newly announced "Mansions of Madness" game, the picture shows some familiar miniatures -- a couple of the Arkham Horror investigators, but unpainted. That suggests to me that people who would prefer to either save money or paint their own miniatures will have the chance to do so, at least with some of the figures.
Unpainted minis?
A little more looking around turned up this line:
8 Investigator Figures and 24 Monster Figures
So it'll just be eight of the 48. But surely everyone will want tentacled monsters, too.