That is absolutely no different then what Walmart charges for something that you can get cheaper online.
It is no different than what we pay for gas when in the middle east... it is 10 cents a gallon.
There are markups on everything. It is up to the individual to educate themselves in a way that allows them to save the most money.
I guarantee you though... that if a part breaks in your PC, you will be thankful they are there, and you dont have to wait 3 days for the part to arrive via Fed Ex.
And as far as newbs are concerned. Someone who has no idea what to buy is going to feel more comfortable walking into a store, talking to someone face to face, and leaving knowing they bought the correct part.
You all take your knowledge for granted.