newegg, zipzoomfly, amazon, and buy.com are my vendors of choice. I've bought and sold enough on ebay to get 100 feedbacks and I don't like ebay that much. It's good for hard to find stuff, but it's often very slow shipping, very expensive shipping, etc.. that really irks me.
Plus you have to wait 5 days for the auction to end, only to get outbid 10¢ in the last 5 seconds by some douche without a job who can sit in front of the computer all day.