Considering we are in the last stretch for the Darkspine event, with only 3 days and a few hours left, and there hasn't been a single comment from staff on the bug reports regarding the discrepancy in prices for the 4 soft-retiring companions, I think it is safe to say this was intentional. And as such I would like to officially make the suggestion to lower the price to be in line with previous events.
Yes, during the first event (Icerun) the prices were also at this level. However, after much feedback of the community, the prices were retroactively lowered at the end, to make the event more manageable, so to me it seems weird that they were increased again for only this event.
So in short, please lower the prices of the 4 companions to be in line with how they were during goldsea and murkwood.
Seems like it was a bug after all.