Autographed banjo heads seemingly add no value to a banjo . Earl and JD signed the inside label of bunches of banjos. The label does help the resale value but I don’t think the signatures add any significant value .?

I know that if I signed your instrument, the instrument would add significant value to the signature!

as a general rule ,, they are right.. now if you got a buyer who is really into "insert hero" then you may add a few bucks but really thats the only case as far as banjos go.....
now if you had a hohner madcat signed by prince then you a looking at big bucks

Memerobilia and good instruments are two different things. (In my book)
The signed guitars on display at the Hard Rock hotel are shiny inexpensive models.

Personally, I agree that autographed banjos have no added value.

Isn’t signing a banjo head, or an electric guitar pick guard, and thinking it increases the instruments value, kind of nuts? Earls signature on a banjo head could be installed on a bottle cap, or a Mastertone. I think just the head itself hanging on the wall would be the value. If Keith Richards signed the pickguard on my Telecaster, I’d take that pick guard off, and put it in a glass case. Then buy another pickguard for my guitar.

Steve Martin played my banjo. That only adds sentimental value to me only. The guy I bought my banjo from, said he drove down to the Deering Factory in 2013, and purchased it off the showroom floor. Janet Davis herself sold it to him, and told him that Steve Martin had visited, and my banjo was one of the banjos he had played while trying several out. Is it true? I have no idea. But it makes me smile to think about it. I just wish he would have signed it…

In the early 2000s, I purchased a 98 Gibson ESS from Curtis McPeak. When I took the reso off, there were 3 signatures in black sharpie...Curtis's, Bela Fleck's and Earl's. I realised that while these are great conversation pieces, it really didn't add any value to the instrument itself.

I’m not sure I agree. Perhaps the signature itself may not increase the monetary price, but If I had a choice of two banjos and one was owned or extensively played by a player I particularly admired (documented), I would pursue the purchase of that banjo before the other. Also, keeping a lineage record of where a banjo has been, what was paid for it, when it was built…. any story regarding the instrument would be of value to me. I have gone to some length to document what I can of the instruments I own. Monetary value? Not sure a signature somewhere on the banjo increases monetary value. I think it will help it sell faster. Of my banjos, Bill Sullivan signed the resonator of a Greenbriar archtop, I was pleased to find after the purchase, and I think Geoff Stelling signed one of my banjos, will have to look. The stories and ownership path (documented) make instruments more appealing to me. And I do own a Nechville that I bought from the original owner because his prominence in the progressive music scene. I was going to add a Nechville anyway but his ownership prompted me to buy that one specifically. I have had various teachers and musicians sign a banjo head but for purposes of inspiration rather than monetary value.
As with most things banjo, we all have differing opinions regarding the subject, this is just my point of view.
Willie

The signature itself is of negligible value, but documented provenance of ownership by a famous person can be worth a lot.