Yeah, a number of us have already said the 5900X is actually a good value chip in the line-up.Its more like £50 since the KF is around £230. The Ryzen 7 3700X does edge ahead if you need more cores,and that has been cheaper than a Ryzen 5 5600X. The the Ryzen 9 3900 non-X is around £310~£325 as part of bundle deals if you need a lot of cores.
By extension,the Ryzen 9 5900X is not only cheaper per core,but seems relatively better priced. This is why Gibbo has sold 2X more of them than either the Ryzen 5 5600X or Ryzen 7 5800X.
And GamersNexus repeatedly said the 5800X is terrible value, so much so that they struggled to find a single use case where you wouldn't be better off (due 100% to pricing) with a 5900X or a 5600X. In their opinion (and ours) the 5800X has priced itself to sit on shelves (after the initial rush).
The 5600X is also too expensive, and relative to its 3000 series price, had the biggest % increase of all of them (thanks to a flat $50 extra across the board at all SKUs).