It seems like there is demand for simple search tools that focus on a single product. The big marketplaces don't have good search filters for most products and probably struggle to justify investing engineering effort. Paired with affiliate links, it looks like there's good money to be made building these. I like that these appear to be data-centric instead of review-centric; I don't trust random review websites.

diskprices.com has a good concept but every time I tried to use it, I found that it has too many "garbage" listings (weird brands, 3rd party sellers, obvious scams, etc.), to a point that it would be easier to just search a few reputable brands manually on Amazon.

Again nothing against the website itself, just unfortunate experience in practice.