i only have experience with newegg.com i have always compared prices of other etailers, and few are rarely cheaper(and if they are it's not by much in my experience).
Been buying from them for several years. Never a single bad experience. not one. incredible fast shipping.
Like most other low cost etailers, make ABSOLUTELY sure of what you are getting. if they accept a return at all, it will be with a 15% restocking fee. That's understood sinice it helps keep their prices low.
just do your homework before purchasing and you will be a happy camper with newegg.com!