In some cases, my favorite and affiliated Amazon isn't the best place to buy something. In those cases, I will usually provide a link to a retailer which I purchased the item from unless it's a small difference. But that doesn't mean I couldn't screw it up, and sometimes products / vendors / prices change and my link may not be the good deal it was when I linked it. But unless there's a compelling reason not to, I provide the same link to the same product which I purchased for my review.
However-- and this is the disclaimer part-- while I take my efforts and reputation very seriously, it's better to cover myself by asking you, the readers, to assume I am a corporate shill who will sell you out for pennies on the dollar, and that every blog post earns me buckets of money by tricking you into clicking my links.