Hello,
I've been trying to create a tuning to make the sell prices of the more expensive spawnable gems cheaper, but even after looking around on nraas retuner and cloning objects on S3OC like "gem" and "insect" or any of the invisible spawners I can't find anything at all related to the actual pricing of individual collectables.
Am I looking in the wrong place for the XLM, or is this only able to be changed through script modding?
If anyone could point in the right direction, preferably which object or resources this is under it would be very much appreciated.

The GameplayData package is where all of the tuning for the game is stored- found in the install location for the game, Game > Bin > Gameplay folder.

Open that in S3PE and you can use the filters to search- ie. type something into the Name box, check the box, click Set and then check 'Filter active' to filter the results.
The two files you're looking for are RockGemMetal and Insects- they're table-based tuning that Retuner cannot edit.
Make sure to export them to a new package so you don't overwrite the original GameplayData

Such a quick response!
Thank you so much