Use Google to search for whatever, but usually that will show www.nextag.com and www.pricegrabber.com at the top, so click those links. Buy from whomever you feel comfortable with. I tend to buy from:
FYI - I rarely buy online, new parts as I try to support local shops, plus there's always some sale going down at the big box outlets. On top of that, I shop at local computer shows plus lots of used stuff for many a project from auctions, etc..
good luck -----Willy