I'm surprised no one has responded to you.
If this is legit, you are possibly sitting on a thousand dollars or more with the black lotus alone. A deck made of alpha/beta cards could top $10,000. It really does depend on what the cards are and of what quality.
I would go to a professional to get it looked at and appraised. A signature does weird things to cards, some signatures devalue the card some increase the value. In the end it will depend on the buyer's point of view.
You may want to contact Rudy from Alpha Investments to get it looked at, he may buy it if he likes it.
Good luck with what you decide to do. First step would be to store them properly.