One possible reason for the disparity in prices could be that when you buy from a dealer, you are getting the dealer's reputation and integrity as well as a knife.
If I buy from a dealer, I know that they will stand behind their product, and if I am dissatisfied, they will do what they can to make me happy.
As an extreme case of this, take James Mattis. He personally inspects each and every knife he sells, and makes sure the knife is perfect. In addition, he includes with the knife a check for 10% of the selling price, made out to your favorite charity.
Another thing dealers will do is keep their eyes out for things they think you will like. Jay and Karen Sadow of Arizona Custom Knives e-mailed me one day saying that they had a new Gold Coin Sebenza and wondered if I was interested (I was!!). I also was advised of their AZCK custom run of Chris Reeve knives, and took advantage of that opportunity as well.
So why can dealers sell at retail? In a word, service.
Walt