How about AdWords; can Amazon get 50 bucks a click on a search? Nope they can't, but Google does. I don't see Amazon dethroning Google anytime soon for ad revenue. They could, but I think they'd need a high end site that caters to quality and not peeps looking to save $1.96 on a set of Tupperware.
Generally private label on Amazon has high margins but high competition, in the good niches at least. Everything eventually dies and gets commoditized. People spend 10-30% ACoS all day long, people give away hundreds or thousands of units. Typically people will buy amazon ads at breakeven or worse in order to gain sales rank to get more organic sales.
>can Amazon get 50 bucks a click on a search?
Google is only getting that on cars or enterprise software or other things with high purchase prices. If Amazon sold cars, I'm sure they'd be able to get people to pay 50 bucks a click.
This is a very important point. I sell on Amazon and I run ads at break even profit to get more organic reviews and higher sales rank. Much more retained value compared to paid search engine ads in ecommerce