I love Amazon, I love both buying and selling so not trying to criticize Amazon. Amazon is not an "auction" site like eBay so its not a knock against Amazon so much as just a difference in how the programs and sites work.
Moving from eBay to Amazon however, many sellers will find it troubling how all sellers selling the same product are paired on one listing. This leads to just the person with the lowest priced item selling which leads to everyone undercutting prices until nobody is making money.
There is one way to beat this or get around this which is private labeling so you can sell your own products and nobody else can piggy back off your listings.