What would you say the estimated price of a piece of rare turquois sea glass is?

I was at Miami Beach with my family and my cousin Danny and my sister Alex were looking for seashells in the ocean. I was doing the same when I saw something sparkley burried under some sand. I picked it up and discovered it was a piece of turquois sea glass, not only that, but that it was pretty rare. What would you say the estimated price of a piece of rare turquois sea glass is?