The reaction from sellers has been understandably fraught, with many saying it's going to cut directly into their bottom line. For its part, Amazon says that the change here is to protect customers and make sure they aren't burned by a bad purchase.

"We want customers to be able to shop with confidence on Amazon," a spokesperson said to CNBC. "For certain products and categories, Amazon requires additional performance checks, other qualification requirements, and fees."

If that means fewer people wind up with knock-off goods, as a customer, it's hard to complain. Just ask basically anyone who's shopped on Alibaba. But! This will have an impact on smaller merchants, creating a schism between bigger sellers that can afford the fee and those who cannot. If this goes more widespread beyond things like running shoes or TVs and into smaller items like music and kitchen items, for example, it's possible we could see less selection, higher prices and fewer sellers overall on the digital emporium.