HI Wayne you are not alone 😉
The sign is an incredible find, AK stuff is sought after especially breadboards, as is any sort of advertising sign, I think what you have there definitely has value but how much? that is anyone’s guess unless you could perhaps see some past auctions on ebay perhaps?
I’d say is is scarce as hen’s teeth, I am not sure how valuable a hen’s tooth would actually be if you found one. If you put that thing on Ebay it would be seen perhaps by some AK breadboard collectors and perhaps some with deep pockets?

at one time there was an AK collectors forum that had a lot of info but I think what may have happened is someone bough the rights out for the AK name and perhaps closed the forum?

for several years I have tried to piece together all the parts to build my own AK 12C breadboard. I managed to collect every single part except the two tube island, the one with the larger Knob. I was never able to find the remaining part. i do have some appropriate mahogany to make a new board and there is one in the SPARC museum that I can use for some comparisons.

I started the forum in PHPbb but it was then changed to this format. It was hard to get people using it initially I spent many hours working on it. At one point it was pretty active. It is still in use. All I can say is yes please do return and make posts, it is not a dead forum and it isn’t being taken over by spam either. I think we all realize that the readership isn’t what it could be , but we can change that by posting and also by encouraging your radios friends to use it. It is in use and there are people visiting it but the frequency of posts could be better. How can it be improved?

Phil