Two things I reckon are pertinent and interesting about this observation. Firstly is that Amazon prices fluctuate with demand. There is no fixed price on Amazon (most of the time) and most sellers will have repricing software that takes advantage of market forces. That means, when you took your picture there is either a higher demand for black skinned dolls or a supply issue. Either could be true. I think given the prevalence of adverts, it's likely teh former.

The second thing is possibly linked to the first - if there's a higher demand for the dolls and Amazon is making higher sales, it likely knows exactly what it's market is. At the moment, the market is clearly white people who want black skinned dolls for their children. As you've pointed out, there's nothing inherently wrong with that - but here's the kicker. This is what identity politics anti-racism looks like. It looks like commericalised ham-fisted poorly thought out assauging of guilt in the easiest way possible. Look at those smiling kids with their black-skinned dolls, aren't we good parents! Thank god we're the 'good guys'.