How do you know you actually have legit Black Beauties? There is no set price for an Improperly Annealed coin. They are worth what a collector is willing to pay for them.
I never have seen a "black beauty" before. I think the blue proofs are worth more. If one of your coins was authenticated and slabbed by PCGS as a mint error, I would be more inclined to appreciate it. As it sits, I'll bet nickel can be chemically darkened.
Hi there, bought a bag off old coins at the local pawn shop. About three pounds for 25 bucks and the blackest one I've ever seen was in it. Also two 1909's and a 1914 d.
Of the major TPG companies I believe ANACS are the only one that uses the term on their label. Google Black Beauty ANACS and you will see many. Here is an example (not my slab)
When you post a coin for others to evaluate please remove it from the holder to image. No one here can give an honest opinion when looking through plastic that has glare on it. As for your question paddyman98 is correct in his reply . Value on these are only what a buyer is willing to pay .