Check your local bookstores for Disneyana price guides. They should be in the collectibles section. Also, Tomart has published a magazine guide for Disney pins. This would be found on the magazine stand. I'm not sure if they list values in there, though, or how up to date they may be. Values of newer pins are very fluid, but I would imagine that values for the older pins are more stable.
Failing that, you can try a search at pinpics.com and see if the pins are listed there. Pinpics doesn't list monetary value, but you can get some idea of the tradability of the pins by looking at the members trading vs. members wanting.