[delecti]

That's a totally valid concern, but Amazon gives you a bunch of opportunity to avoid surprises. They send an email a few days before finalizing your upcoming deliveries, and you can review the price to see if it changed, and either skip a delivery, skip a single product in a delivery, or cancel a subscription entirely.

As a real example: my subscriptions are on a 2 month cycle, and get delivered roughly on the 3rd, which gives me until the 26th of the preceding month to make changes. On the 24th they send an email with all the prices that will be charged if I don't change anything. With almost no friction, I can change or cancel anything up until the 26th.

[brewdad]

I have had the price change between the review day and the shipment day. It was less than $2, so I never bothered trying to get the old price. I've since canceled my Prime for a number of reasons, so it's all irrelevant now