Another good way is to mass purchase from other retailers "first" edition, buggy components and offer the product name at low prices. You don't get the latest version of the motherboard or whatever and you spend a lot of time correcting problems that have been corrected by the manufacturer in later versions. Another is as happened to me, is to offer great prices (an Antec P160 case) and not bother to mention that the case is not new. The hassle of returning the case was not worth it so I just accepted that for the price, I was still getting a very good chassis.
How did I know it wasn't new? The 5.25 drive covers were already removed in the two top slots, there was a nick on the front of the bezel and one of the bezel's top plastic catches was broken off. I will still buy from ZZF but I am very wary about the product I order. I will pay more at NewEgg where the service and product quality is almost impeccable.