I received from a gift box, and I am unsure how much to price it for. Any help would be appreciated :)

Hmm thats a tough one, since I looked on Subeta Lodge and apparently an achievement prize for turning in 500 books for reading contest which I assume was the former reading drive which no longer happens. Which the achievement is also retired, as well.

I would probably say 300 to 500 million for the Papyrus, but I'm sure if you held onto it the prices would likely go up eventually seeing how it mostly likely won't be re-released through the achievements.