You might want to post this over on the Collectors Forum.
In addition, check out PinPics.Com. It's a fan website with pictures of tens of thousands of pins, Disney & otherwise. People can go on there to do research on their pins, see how rare they are and even set up trades through the Trade Assistant.
I'll try to explain how it works...
Let's say you have a 2002 Donald Duck LE (Limited Edition) Valentine's Day pin with Daisy. You put those parameters into the site's search engine: Donald Daisy Valentine's 2002 and you'll get a listing of all the pins that fit those requirements. Then you go down the list, clicking on the listings & looking at the pics that come up. After you find your particular pin, take a look at "Members Wanting to Trade" and "Looking for" (or whatever they're called). If you have a pin that 500 traders want and only 1 person has? It's probably pretty safe to say that it's a rare pin. But if you have a pin that only 10 people want & 500 people have...then it's not as rare and not worth as much in trade (or on EBay). Once you get your pins' PinPics numbers you can even try to look them up that way on EBay. A lot of sellers will use the PinPics pin # i their listings. You can see if they're selling and for how much.
hth,
agnes!