While I agree that sometimes Ebays prices fluctuate based on various factors, its the most up-to-date marketplace for buying & selling pins, so I personally use Ebay as my barometer. I love PinPics too. But simply relying on the number of people wanting & trading certain pins can be misleading. Ive seen pins on many peoples want lists that would sell on Ebay for $5 or so. Since you mentioned that one of your pins went for $100+ on Ebay & you want to see if you have any others, Id check Ebay. Books can be misleading as well since in the collectibles market, prices can fluctuate much more frequently than the book gets updated{most of the time annually}.