I always buy stuff online and while surfing the web for hours for information, the pros and cons and reviews of the product, I always come across this link many web forum members post. (It's a direct link you should keep in your files.)
ResellerRatings.com is a website that rates and documents customer reviews of most online vendors. When searching online for a product (especially an expensive one), if the price seems too good to be true it probably is! While most vendors offer fair prices, sometimes you'll come across ones who use the "bait and switch" method. What they do is offer a certain product (say, a camera) at an incredibly low price compared to other prices, then you purchase it, and they either send you a different brand, a used item, or they don't send it for months and you're left to go with a lower-quality product that they happen to have in stock.
So, just be sure to buy from a trusted vendor!