Amazon marketplace is a bit like eBay: you can buy new and used goods, but at a fixed price rather than an auction.
I used it today for the first time because I happened upon Amazon’s mobile site.
Amazon marketplace products are much more prominent on the mobile site. To my eyes they also look more “official” and “premium”.
The result: instead of overlooking them, I browse and buy from Amazon marketplace for the first time. Instead of spending £21 I spent £9.50 (for an identical, brand new product).
The interface drove the decision: context, not preference.
Amazon’s legendary user experience costing them profit? Now there’s an irony…