Well this is anecdotal evidence, i doubt this has any impact on the overall Sales. I understand some people buying a second console, if you stuck with older model you might want to get a Jasper to reduce noise, heat etc. etc. etc.
Dude think what you wrote there, PS3 is EXPENSIVE even for people with decent jobs, because for majority of people spending something like 299 pounds on a product is a big deal.
Look, looking at annual GNP (income per capita) figures in the United states, it is around 50.000$ per person in 2008. That means the average American makes about 4200 a month. 1050 a week. Is 299 or 399 or even 499 such a big deal when the average person makes that amount in less than 2-3 days? And that's the average income, there is a sizable portion of the population making well over that amount. 399 is a few days worth of work at most. Burger flippers don't count.
Income Per Capita is not really helpful here, because it mixes those really rich with the rest it does not reflect how much money majority of people have (it's usually lower then GNP), so do not look at that. Plus like others have said there are so many spendings in every week/month that will make a purchase of a console a big deal, because budget needs to be balanced. It seems easy when you're single with no kids and have a good job that can support your hobby but thats minority of people.
Price is a major factor and PS3 is expensive, if it was not it would not get such medicore sales during the Holidays, when 360's are selling like hotcakes because of the cheap arcade model. Holidays do cost a lot of money, so people choose more economical product as a gift.
Im in University at the moment, and recently i've bought a DS then i had to starve (well maybe it a bit less)for about a week and not get wasted as usuall for this same amount of money to make up for money i've spent on it.