Sometimes completed Ebay sales can be a good barometer of what items are worth. Some may suggest that Ebay sales can be on the lower side of worth but it does show what some will pay. The problem with some price guides is that many are produced yearly which may not show any trends up/down. There are weekly publications (baseball cards) that can help.
My suggestion is that if you have a large collection, look for a book (price guide for this year or last) for sale on Ebay. Use that as a way to sort through your collection and pull ones that appear to worth more. Than you can use Ebay completed sales to see if any similar have sold. Of course these publications are general ideas of what things may be worth. They are only worth what someone pays and condition, availability and rarity play a lot into values. It might be worth contacting any local stamp collector shops YMMV or ones online you can call to point you in the right direction.
-Good luck
- Be careful of those who support Luigi.
