According to Subetalodge, its an achievement prize during the Reading contest. None in shops or trades. Thinking of selling it and need a bit of a guide.

I bought the last one off SS maybe a month or two ago for 75m.

I think its probably worth at least twice that because its not available from any other source currently but i wouldnt be surprised if it was eventually added to the antique shop because its from a reading drive ach.

some top readers will spend big bucks, but im not sure if any still need that book.

TL;DR 75-100m for a quick sale, 150-250m if you want to wait for a buyer, but dont wait too long (year+)

Thank you so much for the advice.