If you head over to Gamestop, you would notice that Portal 2 has had a price cut. The console versions are now $39.99 while the PC version is at $29.99, and Bestbuy is doing the same thing. But Amazon is pushing it and have the consoles going at $34.99 while the PC version is still $29.99.
Not sure why this is exactly happening, but don't let this deal slip by, get it while you have the chance.
they have too much stock as most people purchased off steam