The best way to save money on prime is to not buy stuff. Seriously.
I have a small list of items I think I will need in the near future; if it's not on that list, I'm not buying it, from anywhere, at any price. Maybe I'm a bit more ascetic than the average person, but I find it hard to imagine people just browsing lists of "cheap" stuff for hours to just buy stuff they don't need. And then being happy that they won because they paid less than some imaginary "full price".
If you may or may not have food tomorrow, but there is a lot today, you stock up and eat.
This works great in the savanna, not so much when a trillion dollar company is using it to exploit you.
Need a new blender, because the old ones sounds like a woodchipper? 5 days until prime day/cyber monda/black friday/christmas sale... well, let's wait and we might get a deal. Now you know that you didn't have to wait, because you're not getting a deal.