When I worked, my office paid for Amazon Prime for me since I did the ordering for the company. I let it lapse after I stopped working. I only used it to save shipping time and cost.
If I ever want to buy something from Amazon that I need in a hurry or has an especially large shipping cost, I'll renew. It's been over a year, and I have found that I can live without it. If I'm willing to wait, I'll put an item on my wish list. When I have $49 worth of items to buy, I'll get free shipping on all of them. Otherwise, I'll pay the shipping costs. One would have to buy alot of merchandise in a year to break even with the $99 fee.
I've also found that the items listed as Prime often are not the least expensive. I think they increase the prices to make up for having to pay for the shipping.
There is also another option. One could sign up for a monthly fee of $10.99 that can be cancelled any time. If one wanted to buy an item with a large shipping fee and needed it fast, that could be a good option. It would need to be cancelled before the month end. I'm sure Amazon thinks that most people will forget to do it before their credit card is charged for another month.