I don't even think it has much to do with the economy. PS3 doesn't sell well because it isn't marketed as something that people want. Wii by its very name is a very wanted item because that's just how it is. That overrides the economy factor. Even 360 has some sort of hype advertisements with its games, like Gears 2 (although it has been a while).
Unless people see some kind of need to buy the product, then you're not going to sell. If people don't need you, than you as a business will not survive. Entertainment, as funny as it sounds, is a human necessity like food and water and shelter. People will always be in need of entertainment, especially in economic downturns like we see today. But PS3 doesn't market itself well as good entertainment. It markets itself as more technology, and so it's bound to not sell as well as Wii or even 360.
"Faith is the Essence of things hoped for; and it is the evidence of things not seen"
