Purse lets you find discounts on Amazon when shopping with Bitcoin. The way purse works is that they match up your BTC order with someone purchasing on Amazon with a giftcard. https://purse.io/shop
Almost everything you can buy on Amazon are things that you should be able to find on Purse. The discounts for paying on Amazon through this website can be large depending on how much you're buying.
The reason it is cheaper to pay with BTC on these sites is that the taxes for paying with Bitcoin on these sites are much lower, and therefore you will be able to find better discounts on the products you're looking for.
Here is an example of a discount that you would be able to get if you pay with BTC instead on someone's actual Amazon listing. The discount is not guaranteed, but the website states that at the current time most discounts range from 10-15% off the current price on Amazon:
Here's another example of headphones that are $3 off depending on what kind of discount you want to try and negotiate for.
You can also connect the CoinBase, Facebook, or Google+ API if you want to make it easier to pay for your orders with crypto. Although be aware of tracking, etc.
If you still find Purse confusing, then basically the way it works is that you send BTC to Purse, someone makes the purchase on Amazon with their giftcard, the order gets delivered to your residence, and then the funds in your Purse wallet are sent to the person who purchased on Amazon with their giftcard.
You recieve a discount on your purchase from Amazon, and the giftcard holder gets BTC in return for their assistance. https://purse.io/how-it-works
This is not the only website out there doing this, but this is one of the more professional looking websites.
Also, if you have a huge balance in Amazon gift cards, you can now relatively easily exchange that gift card balance for some BTC or Bitcoin Cash. https://purse.io/earn/btc
Not financial advice, please do your own research.
You can also download the Purse extension for Chrome to easily add items from your Amazon shopping cart: Chrome Extension