For fun I check eBay every year or so. I've seen them on there anything from $50 sometimes, right up to $3600 I think was the highest I've ever seen. Average is around the $1000 usually. I think it depends on whether it is first edition or not, or signed by Brian at an airshow etc.
Hang on to your two - could be a better retirement plan than crypto currency! :D
Would you be willing to lend one out to be scanned for the Internet Archive? I have no relation other than finding books to be digitized and paying for/coordinating the scanning.
I’m willing to provide insurance and proof of my identity to ensure your property is respected.
How does one go about doing this? I have access to some obscure technical books that really should be scanned and archived, but don't know anything about the field...
I have temporarily added contact info to my HN profile. Please get in touch if you would like me to help facilitate the shipping, scanning, and return of your book donation.