You can use a service like purse.io to buy things from Amazon. You pay bitcoin and someone else uses their credit card to buy the item and ship it to you. You can also get some discounts there since some people are willing to pay more for Bitcoin.
So does Purse.io buy the amazon item for you?
You put up an order on purse.io and if someone likes and accepts your terms (how much bitcoin you offer and the price of the item) then they buy the item for you and the Bitcoin is kept in escrow. Once you confirm the item has arrived, you release the Bitcoin to the other person. It is a p2p service.