How much is it worth?

Two weeks ago, I happened to overhear a woman asking about sea glass. I was at Jo-Ann's Fabric. I couldn't help it. I piped up, "I have sea glass". We spoke for a moment and then she gave me her card. Conveniently she lived in my community. After a few e-mails, she was looking for an accent piece for her bathroom, I created this. She liked it and today she picked it up. I charged her $50. Was that enough? How can you put a price on polished glass that brings such bliss when it is found nestled in the sand?
But I liked her and I think she really liked the piece. My first sell!