Haha! He was an elderly guy and had no idea about the West points. He did some research on his PC and said, Why Not!
In my area a W anything is $15.00. Given what a half is worth today you should have gotten two of them. His research paid off, for him.
I can't say for certain, but I would tend to think that the current craze for W quarters is short-lived and the values will go down. You might have gotten a bit more on Ebay... but, in the long run, I think a circulated Walker is a great trade for a W quarter.
To the antique dealer, it’s not just a 2020 coin. It’s a limited edition coin with only 2 million minted and a mint mark with a “W”. It’s worth more than the silver coin he traded.