How should i value my recent edition of Mary Poppins signed by P.L. Travers?
Put it up on eBay with a really high reserve. You pay to do so, even when it doesn’t sell, but you will get a kind of valuation out of the bargain. Also contact rare booksellers and ask. I doubt you’d get too much play for an unremarkable edition that is signed. It’s just too similar to selling an autograph. Signing comes into play for already collectible editions of books, separating the really valuable 1st editions from the only-perfect-condition 1st editions.
You can check what similar copies are going for at Abebooks by using the advanced search and selecting the characteristics that match yours (eg. year, hardback/paperback, dustjacket, signed). This at least gives you an idea of what other people are trying to sell theirs for. Signed copies appear to be going fom US125-$2100 depending on other things about their condition and particular edition.
