How do your shipping prices compare to Amazon's? Not good news: you're probably paying 300% more. That's like it buying an item at $100 while you pay $300. Today's WSJ does an expose on shipping charges.
These different shipping rates are one reason Amazon can afford to offer "free shipping" -- free shipping for it costs two thirds less than what it costs you. When you start talking next day shipping, Amazon's clout has even more benefit: you pay about 600% more in shipping charges.