I'm in the industry, I hear people talk about ads all the time. The $25 per action is from a talk I was at 2 weeks ago from someone doing 8 figures a year on shopify and a ton on amazon as well who made this point specifically.

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.