I've seen signed copies of the standard edition for $100. (I got one at a photo gallery.) In fact I've never seen one unsigned. You've done very well finding them reduced or used. The first one I bought was Claxton's "Jazz". I kept telling my friends and family I wanted it for Xmas or my birthday but to no avail. Finally bought it for myself but by then it was 2nd edition.
However, much to my surprise and delight, someone for whom I'd done a favour repaid me by giving me Herman Leonard's "In Memoriam" portfolio. Later I bought a print of his famous portrait of Dexter. The print I regret not buying was the Wolff photo of Coltrane that was in the first batch that Mosaic sold. It's cropped on the cover of Blue Trane. Finally I found a poster of it on E-bay.