The "dynamic economy" they added in this remake is fucking retarded.
Prices scale depending on how many goods of the same kind you are selling is an egregious design mistake the team made.
It's a bad idea in principle, since the last thing you'd want would be to create reasons for the player to meta-exploit your system while doing tedious work (as rotating from a camp to the other just to keep the prices at their highest)-.
It's even worse for how aggressively it has been implemented here, with a lot of common items instantly crashing to virtually ZERO value after selling not even a full stock of them.
What's demented is that price fixing doesn't even happen after a sale but dynamically DURING it, whic means that you may be selling 80 of a certain item without even realizing thart at least 40-50 of them are being sold literally at ZERO value and so basically given away for free to the merchant.
It also makes all the "trophy gathering skills" you spend valuable learning points on basically useless.
There's a mod on Nexus currently that swaps back to "fixed prices for everything" and since I started using it I never looked back once.
https://www.nexusmods.com/gothic1remake/mods/54