Well, all you have to do is look into 3rd party reviews of Newegg. It is not like eBay. They are the top rated online computer retailer in the USA. I buy all of my computer parts from newegg, and the few times I've received anything bad, they replaced it with no hassle what so ever.
Additionally, buying those same parts suggested by Zek, and the others, in a normal retail store will almost double the price.
While many of us may be amateurs, a good majority of us are not. I, myself, am 30yrs old, and have been building and trouble shooting computers since I was 14yrs old. I am, by no means, a professional, but I am nowhere near an amateur, either.
To buy these pieces in a normal retail store, when you can buy them from a well documented, fully respected online store, for half the price, is absolutely ridiculous.
For looking up the credibility of Newegg, I suggest starting at the Better Business Bureau.
In fact, here's the link:
http://www.labbb.org/BBBWeb/Forms/Business/CompanyReportPage_Expository.aspx?CompanyID=13146135