I like the idea of using crypto to pay for stuff, but I dont understand the lower cost part. Why would the cost be lower compared to just buying directly from Amazon? Where is the extra money coming from?
The extra money comes from the brokers. For example, if you were to place order on a $100 amazon product, you might only need to pay $80 worth of ETH. A broker who fulfills the order will make the purchase from amazon on your behave using fiat of $100, and in return they receive your $80 worth of ETH. That $20 different is payed by the broker.