In regards to finding a good starting point when you have the only known copy on the internet, are there any good resources where you can find the information about its particular print run??
For example: Book "A" was printed in 1970 and it does have all the usual indicators to show its a true First/First. But there are no other copies found on the internet. What do you do?
You could set a so-called high price of $200 and wait til others show up on sites like Addall.com or Bookfinder.com etc., then reprice accordingly.
OR
You would use a resource that would tell you how many copies were run on the first printing, explaining how rare your copy is ...if such a resource exists for various publishers.
If you had Book "A" and you priced it at $200 but later found out there were only 500 copies made and yours was signed by an above average writer, your price would most likely skyrocket. But without a good resource or other copies to compare against, you could easily & unwittingly underprice your gem of a book and end up leaving money on the table.

Has anyone ever heard of such a resource?

Kyle