Bottom line is: they're worth what a person is willing to pay for them. If you think they're worth more, then you get to keep them until you find a person who agrees with you (or that you agree with them). Value is not set in stone. Despite what Kelly Blue Book, or an appraiser, or what something else similar sold for, an object has 2 constantly changing values: 1) What it's worth to the buyer; 2) What it's worth to the seller. When the 2 agree you have a transaction. - 2 cents (off soap box now)
No offense to anyone who asks "What's this worth?", but I think Coby has given one of the best answers of all time. I've tried to say this before, but never as well. It reminds me of the Antiques Roadshow and similar programs, where an expert will tell someone what something is worth - but they don't buy it. Items are only worth as much (in dollars) as someone else is willing to pay.
Good luck and take care.