When selling to a teraton nest that has a factory the line showing the discount or markup of the item is not shown in their trading chamber.
If you go to a teraton nest that has only a trading chamber, then it does show. Have not yet encountered a nest that does medical experiments, if it exists in this game I'll try to sell there too.
Savefile available on request, attached are screenshots of two separate Teraton nests (in the same system)
Transcendence version 1.7