Yep, cut my impulse buying back since they upped the free shipping threshold again. When it was $25 and $35, I would buy a lot of small impulse orders. Now I have to wait until I think I really need several items to hit the free shipping threshold at $45. I'm an old cheap bastard I guess. If there is something less than that that I want but don't desperately need, I add it to my cart and leave it there. After a while when I have 2 or 3 things in there and get over the free shipping threshold, I complete the order. I've had 2 things in the cart for about a month now. I would think Amazon has lost a lot of impulse buys with the higher threshold.
Back to the point of buying a Sold By Amazon product.... On the left side of the amazon screen there should be a bunch of filter options you can choose. Scroll down to there is a way to show only items sold by Amazon, or select the prime eligible. Either way would work.