Hills Brothers Cinderella Castle value?

When my Mother died in 1988 I found in her belongings a long unopened box w/1959 postmark.  I opened it to find a Hills Brothers Cinderella Castle, fully intact.  It's a little yellow around the outside paper edges but perfectly dry and flat.  It's still in the original box mailer.  I remember playing with one as a kid but obviously my Mother got a second one and tucked it away. Can anyone direct me to a Disney source for me to find out what the value might be?