Was this topic a trap? Because if so, its hilarious. PC Gamers on this site love to espouse how superior the PC gaming experience is over the console, yet here they are forced to either admit that there is nothing special about PC gaming (thus supporting its lower price) or stick to their guns and accept a higher charge. And they can't even fall back on piracy, due to their love of saying how it "doesn't matter". Really, its all quite delicious.
That said, I don't think any medium is inherently superior to any other, but some games certainly are. I'd have no problem paying $60 on any format for a game that was considered AAA in quality and development costs, but I'd never pay (and never have) the same amount for an objectively inferior game. Just as you wouldn't pay the same price for a Chevy Nova as you would a Porche 911. Some parts of the industry have caught on to this (no indie developer in his right mind would ever charge mainstream costs for his game), but many other aspects of it have yet to catch on. Sales figures should effect the price, its simple supply and demand. If no one is buying your stuff, either make it better or make it cheaper.
Do what the grocery stores do. If you know your game just can't compete with its immediate competition, no matter what you do (say, the newest Medal of Honor vs. CoD: Black Ops), then don't market it as a competitor. Market it as the bargain brand version of the other game. Sure if both cost full price then most people will go for the better game, but if your game is suddenly half price, then you become the much more tempting choice.