Mariah

Hello, I've recently found a 30 kopek/2 zlote 1836 coin in excellent condition. I've no idea how to value this coin, and intend it as a gift to my father. Would you have any knowledge as to the value, or how to direct me to an appropriate, (trustworthy) site or dealer to have it appraised? Typically, I've purchased U.S. coins for his collection; we are of Polish ancestry, and I know he'll enjoy this, but we always enjoy the history....it adds to the value for us. Thank you so much.