Prime day is a scam.
I had about 20 items in my cart for the past two weeks or so. I watched the prices go up a couple dollars every few days. Then, TUH DUH, Prime day the prices went back to the price they were when I placed them in the cart.
I always check https://camelcamelcamel.com for Amazon historical prices when i don’t need something right away. If the price changes a lot you can have it send you an alert when the price reaches your target.