There are two cognitive biases that cover apple very well.
http://en.wikipedia.org/wiki/Post-purchase_rationalization
http://en.wikipedia.org/wiki/Confirmation_bias
It's very simple really, people who purchase the more expensive item rationalize that item by understating problems or shortcomings and overstating benefits. This is the only way they can not feel "bad" about their purchases. This is highlighted by self-report studies.
A good example of this is my wife. She had a 2001 Honda Accord. That generation was well known for transmission issues (they effected Honda and Acura) and eventually it affected my wife's car. Luckily they replaced the transmission post-warranty and even extended the warranty.
Now, if you asked my wife (self reporting) how many problems she had with the car she would state "zero". Why? Because she doesn't want to acknowledge that a car which she researched extensively and believed in would have a problem. Since Hondas are known to be reliable cars she had cognitive dissonance as to her own car's unreliability. This dissonance was resolved by saying they fixed it. Yet the car still had the problem, it was still unreliable, regardless of the fix. Had it been 1-2 years older I doubt Honda would have fixed it, even if it would have been as a result of a problem they knew about.
You could also say this is the Consumer Reports affect.
Naturally the opposite of self-reporting, confirmation, and post-purchase rationalization is 3rd party confirmation of reliability on a statistically significant level, controlling for exogenous variables. The best party to study this would be a warranty company, luckily we have a 3rd party warranty company that did study it.
http://www.squaretrade.com/htm/pdf/SquareTrade_laptop_reliability_1109.pdf
Hmmm...interesting, eh?
I know a used car finance company that self-insures warranties, I have asked them repeatedly for their warranty info information. Naturally they won't release it but I tease them about it every time they come into my office for a meeting. Why? Because I would rather get past the BS and boil it down to a disinterested 3rd party.