Like I said earlier in this thread, we've had Prime for 5-6 years and would spend a few hundred dollars a month with Amazon. We even use their subscription services where things you buy routinely are shipped to you at set intervals - every month, every other month, etc. I was impressed with Amazon from the time I first used it back around 2000 or so. Should have bought stock in it back then -oh well.. Excellent customer experience and service when you need to deal with them.
But, For us, the price increase basically woke me up to shopping around more before we decided whether to keep it or not. To my surprise, there are just as good or better deals out there most of the time with free/low shipping. I know some people are wary of e-bay, but we have not had any problems so far. I truly believe e-bay has stepped it up with more "buy-it-now" pricing, free shipping, and pay-pal check out to compete with Amazon. Don't know how they induce sellers to list that way, but I won't bother with bidding or "make an offer" on new items. I'm careful to compare actual model numbers, etc., when shopping e-bay, and look at the seller's rating.
As for Amazon shipping, I have seen more and more items delivered by USPS, often via hand-off from UPS. I can't really recall any major delays however - maybe a day here or there. My problem with USPS is that they will leave items hanging from my mailbox or on the open door of the mailbox. It just begs for someone to swipe it. UPS will always deliver to the house/garage. Don't think we've every got an Amazon item via Fedex for whatever reason.
Anyway, we may go back to Prime at some point, but for now, I'm shopping around for anything more than $25-$50 before I just place an order via Amazon. I am curious to see what their financial results are for the 2nd and 3rd quarters this year to see what impact the Prime price increase has had. To each there own, and it's great to have competitive choices for on-line shopping.