8 million tops, I would bet more like 3-4. SMG was being developed for years by some of the top programmers in the world and only cost 15 or so.
3-4M for the Conduit? You realize that 100K/employee/year is the standard, right? 15-20 employees for 2 years then on the Conduit? And of course they get their motion capture, etc. for free, right? Mocap studios love giving time for free.
Lets use GTA4 again as an example, while we're at it. Most of that $100M... voice acting, actor mocap, licensing. If you can't deduce it on your own, those expenses have nothing to do with platform-specific development, per se, and everything to do with ambition. GTA4 on the Wii probably would have cost $85-90M, at the least, given the same grade of resources.
Production value == cost. It has nothing to do with platform, and everything to do with project ambition. That's the last time I'll say it.