WWs aren't particularly hard to generate and den space hasn't increased at all since launch. (I still heavily, heavily disagree with their implementation vs a rarer but guaranteed system while keeping the knucklebone system intact; it still feels terrible 2 years on from a game dev & player pov. I loathe gacha games, though. I don't expect LW to change at this point, but I will also never stop saying it feels awful.)
So a lot of the super inconsistent WW pricing is probably a combination of that + all the other stuff going on that people have also mentioned before me, with player morale being low, new players not hanging around super long, etc.
More den space is only really "generated" when a new player joins and expands their dens at this point. That doesn't happen nearly as fast as WWs are generated, and players have to start making decisions about which projects are worth it, and which they don't have time or space for. But everyone else on the site is also making those same decisions. So even pretty ones start going for dirt cheap as long as they aren't absolutely stellar. Some people still list much higher for things like ID number or significant birth dates, which is valid! Get whatever you can for whatever you have.
But I've started to see a lot of those get chunked down by more than half (350ms all the way down to 150ms, or I saw one listed for 400 a few months ago back up for 75ms last week) compared to what they used to be listed for weeks or months ago. At some point, even those may start getting released as space gets pinched tighter & tighter. I don't necessarily think they are all overpriced or anything, I think it's more a matter of there just not being room for everything just because it's pretty.