Amazon is significantly more convenient than other sites. I was about to buy my textbooks today using Bigwords and got a total around $220. I went ahead and added everything to the shoppings carts of 4 different websites. Just to compare, I added the same books to Amazon and got a total around $250. That's a big difference so I got ready to make the purchase on the 4 sites, but I couldn't remember my log ins for 2 of them and the other 2 wanted me to create a new account. That did it for me, I went with Amazon. Not to mention I would be guaranteed shipping in a few days while some of these sites take up to 2-3 weeks + slow media mail.