Question about the value of a book from 1920?

among my boxes of things I just discovered a 1st edition copy of "the burgess animal book for children", signed by the author. all the pages are in perfect condition but the cover has minor wear and tear and the second page has a note from the original owner to her grandkids. does anyone know how much this book is worth? there is a note in the corner that says $250- but is that really accurate?