We found a vintage silverplate/mother of pearl C. G. Conn 22B trumpet in the original case at my mom's house this weekend and we are wondering what it is worth. How do I go about finding that out? It looks to be in very good condition. I looked up the serial no. to find that it was made in 1927. It could use a little polish, but all the parts appear to be there and it sounds good. Can anyone give me advice? Thanks!