Sam Sloan is a lightning rod for criticism.

I read somewhere that the reason for the outlandish prices is to protect seller rating. For some reason delisting an out-of-stock book will have a negative effect, instead they raise the price so high that nobody will try to buy it. I suppose if someone did want to pay $809 then they could try to find a copy somewhere for $404.50 and still come out way ahead. Or just fess up. The source didn't go into any detail. It makes as much sense as thinking someone would pay $809 for a chess book. But it probably doesn't explain the sellers who have only high prices.

abebooks is listing the second Benko book under the title Chess Endgame Lessons Part 2, so apparently it's a continuation rather than an update. Only $75.00!
https://www.abebooks.com/servlet/BookDetailsPL?bi=30753842130&searchurl=an%3Dpal...

About this Item
Light crease on front cover else fine. ; The scarce Pt 2 of Pal Benko's Endgame Lessons. ; 4to 11" - 13" tall; 207 pages. Bookseller Inventory # 1000128964

Bibliographic Details
Title: Chess Endgame Lessons Part 2
Publisher: Pal Benko
Publication Date: 1999
Binding: Paperback
Book Condition: Very Good+

I have a copy of Chess Endgame Lessons from 1990, given to me by Benko himself. It has Benko's "Endgame Lab" columns and games annotated by him, up to 1989. I didn't ever verify that it was "all" his columns for that time. The material is good, but there were several things I didn't like about the presentation.

• It's a copy/paste/photocopy reproduction from magazine. Not too attractive, and otherwise there has been no obvious editing.
• The columns are not in chronological order. The month, year that would have appeared at the bottom of every other page has been cropped. This makes it impossible to know the date of the writing, without laborious cross-checking.
• Benko's Bafflers are not included. These often related to the topic of the same month's Endgame Lab, so it would have been nice to include them.

My copy says "[c] 1989 Revised October 1990" and has:

• a brief Biography of Benko on the inside front cover
• Title page
• Introduction by Burt Hochberg
• Table of Contents
• Games index
• Preface by Benko
• Acknowledgement by Benko
• Endgame Lab columns on pages 1-191
• annotations by Benko on pages 192-254

Later Benko produced a followup volume in the same format. Since I didn't like the format the first time, and because I already had all his columns saved in a file cabinet. I never looked at it closely. So I don't know if it's a continuation (e.g Volume 2), or an expansion (e.g. Expanded 2nd Edition).

The Endgame Lab book I didn't even know existed until now. I did find this: https://groups.google.com/g/rec.games.chess.analysis/c/lDptoFXLs2U. Interesting that unlike other Ishi Press publications, it's a reproduction from Chess Life rather than a reproduction from a chess book. From this one fact alone I think Sloan's claim that Benko asked him to do it might be correct. Anyway, Endgame Lab only goes up to 1986, so has less material than Chess Endgame Lessons.

For the price of a single-year USCF membership, you can download all the back issues and have access to all of Benko's columns.