You can simply buy anything by using a credit card based on Bitcoin and/or any other cryptocurrencies. The huge and only advantage brought up by such system is the awesome profit brought up by storing value in cryptocurrencies but for sure at least not the transaction time and cost.
If amazon accept Bitcoin as a payment system it would make a huge noise in the mainstream media and cause Bitcoin to take an incredible value, so it would really be very nice for investors. But I don't see any advantages brought up by being able to pay with Bitcoin for both the users and the platform.
Acquiring a credit card based on cryptocurrencies is the best option.