Knife Center is an excellent vendor. They are fast and honest. Their site has more information than most, and their range of stock is probably second to none. Their prices are not the best in most instances. But, frequently they're real close to the lower prices going out there. You won't go wrong shopping with them. You may just spend a few more dollars than necessary. There are other honest, customer service oriented vendors on the web as well, usually with lower prices.
Am not going to list a bunch, but will recommend a participant, shootist16, Dennis Bible. He sells knives, gives great service, and often has real good prices.