The staff of the Information Sciences Library and the Elizabeth Nesbitt Room are not allowed to provide information regarding the value of books or journals. However, we are able to point you towards several web sites where you can compare the "for sale" values that have been placed on items similar to your own. You should also be aware of several sites devoted to helping you in this sort of search.
The most authoritative site is from the American Antiquarian Booksellers: http://abaa.org/
Several other pages of interest can be found below: