+ here are a couple of ideas. Try seeing what kind of offer that Danbury will give you for reselling them (Hope they were all sold out) and then you have a price to start with. Check in the search engine on E-bay and see what they are asking and what they are getting there. I have seen collector plates at flee markets so you might try one to see if anyone is selling them. Also see if there are any publications that serious collectors and antique people would be reading that might give you a clue as to where else to look or maybe even the value. Danbury most likely advertises in the same publications so it might be worth a call and ask them what magazines and periodicals they put their adds in.
Good Luck