I haven't necessarily found too many things on Amazon to be cheaper than other places. You can check out their third party gift cards,
here, and if you make purchases to a certain store/merchant often or have one coming up, maybe use your amazon gift card balance to buy a gift card from that merchant? Amazon also sometimes have certain gift cards on sale (e.g. we have bought Airbnb gift cards at 40% off. I also currently see Jiffy Lube selling for $40 for a $50 gift card (only helpful if you own a car and don't change the oil yourself)). However, ONLY buy them if you plan on using them in the near future. I have found sometimes you buy gift cards and they sit around and you forget to use them.
Another option is to check out common household items (toilet paper, paper towel, batteries, light bulbs, etc.). I would compare the prices at your local stores first. I have also found that we buy stuff from Amazon for the convenience of getting them shipped to our home. Otherwise, I wouldn't go out of my way to use Amazon.