For what its worth, the 2nd edition of Tomart's Guide to Pin Trading lists the Mouseketeer Contestant pin as having a 'C' value, which puts it somewhere between $36 and $75. The pin you are referring to is Pinpics# 4172, which indicates that there are only 4 people trading this pin, and 109 people wanting the pin. That's a pretty lopsided ratio and indicates a pretty rare pin. I would think the pin would make a very good trader!
Personally, this is the type of pin that I am only interested in if I actually won or earned it. Just like a Continuing the Tradition pin, it means more if you earned it and not just purchased it.