Value of a cowboy hat?

I own a cowboy hat from the Larry Mahan line that I purchased at Vail in 1979. It's made out of pressed beaver fur & is in almost mint condition with a feather hatband enhanced with a turquoise stone. The hat is a silver/gray color. I've heard that these hats are quite valuable now as this quality of beaver fur is no longer available. Searching Ebay has not really helped me determine the value . Can someone please help me with that, as well as how to find sources for selling this hat. I have the original box & the receipt. TIA