I've NEVER seen fresh Chervil for sale ANYWHERE. And probably for good reason since it's extremely fragile & delicate. Wilts after picking if you just look at it. Which is why I simply grow it myself. It's easy to grow - even in a container.
As far as dried Chervil. There's a reason why you can't locate it. While it dries easily, the scent & flavor of dried Chervil is completely worthless. Similar to dried lawn clippings.