Comparing the MW2 sales on consoles vs PC is a bad idea considering how infinity ward butchered the game. It isn't that the PC version is inferior, but rather that PC gamers expect more from their games. Hopefully that is not the trend and that PC developers don't start gimping their PC games to make them more similar to their console counterparts.
PCs are more expensive than a single console, but the prices people quote are just outrageous. People who think PC gaming costs significantly more than, say, a PS3 is ill informed.
As for the cost of PC games, I don't see how it can be more expensive for developers than consoles. Developers don't have to pay licensing fees on their games, which is why most of them are 50$. People don't really buy used PC games. PC games sell new for much longer than they do on consoles. A few months ago, I bought Psychonauts from gog.com. That game is old, and the developers just got money from me on their PC version. Piracy is a bigger problem on PCs, but people also pirate on consoles. Using a digital distribution platform like steam can help reduce piracy for developers.
