I assume youāre aware that āfirst editionā is not the same thing as āfirst printingā. The edition number of a book remains at āfirstā until there have been significant revision changes to the book itself and could have been churned out in large numbers for years. Within a particular edition, the publisher may have been ordering varying numbers of copies in batches, starting with āfirst printingā of the first edition. So, a first edition of a book is not necessarily more valuable than subsequent editions (even if signed); but a first printing a first edition might be if the first batch had a low number of copies produced.
There was a first edition hardback with authorās signature and dedication (dated 1996) that closed on eBay in August at just under $50
https://www.ebay.co.uk/itm/SIGNED-A...83.l10137.c10&nordt=true&rt=nc&orig_cvip=true