I used to order our San Francisco Bay K Cups (coffee) from Amazon, but they have been sneaking the price up a few dollars for the 80 Count box we usually order every 6 weeks or so.
So, I now order that same 80 count box directly from San Francisco Bay in California for $3 less than Amazon, no sales tax charged and free shipping.
Slowly, we are slipping away from Amazon. Even our dog food order is less expensive at Walmart which is one mile from us and where I get DW's prescriptions.
Next year, I drop Prime when it is time to renew.
On the other hand, yesterday I went to the grocery store (which I seldom do), and bought a bottle of Centrum vitamins for $13.98. When I got home and checked Amazon, they had the exact same bottle for $9.99. I could have saved $4 and had it delivered to my doorstep rather than fight traffic and a crowded parking lot.
But today Amazon's price for that bottle is $10.99. I only would have saved three nice crisp dollar bills instead of four. Unless, of course, the supermarket price has changed as well.
I tend to think that no matter where I shop, if I don't check other sources (preferably on that day), then I won't get the lowest price.
I use a few Kirkland products from Costco, fish oil caplets and D3. I had a Costco membership a few years ago and then later had my son get them for me. Turns out you can order without a membership and pay an extra 5%.
Or, you can get them on Amazon! I found both for the same price or less than Costco. These are supposed to be sold only at Costco so my guess is someone is drop shipping or buying them on sale and then selling on Amazon. One of my shipments came in a Costco box from a Costco distribution center in IL.