
Available quite reasonably at https://www.amazon.com/Last-First-Men-Star-Maker/dp/04862196....
Lafferty's critically acclaimed, and has a small, devoted following of readers, but somehow most scifi readers haven't heard of him, much less read him. Perhaps his work is just too strange for mainstream readers, who can only appreciate traditional scifi.
I've tried reading Stapledon (Last and First Men, and Star Maker), and I wanted to like him, I really did. His ideas and sheer breadth of vision (billions of years of history, spanning galaxies) sounded amazing. But when I got down to actually reading him, he sounded so dated, so tedious, so bombastic, so clumsy -- he's just a poor writer. His ideas might be worthwhile, but they're just not expressed well. Given how highly he's regarded, however, I intend to give his work one more chance someday.
That isn't entirely true, Lem praised the work of Philip K. Dick (American)[0][1] and Olaf Stapledon (English). He has two essays in which he analyzes Stapledon two great works: Last and First Men, and Star Maker[2].
I think you might also be suffering from a filter. The best of Polish writers were translated, whereas you have access to the glut of all American writers. It is probably true that there was a greater number of bad American writers.
[0]: http://www.depauw.edu/sfs/backissues/5/lem5art.htm
[1]: Dick returned the favor by reporting Lem to the FBI as a communist conspiracy against the west. Arguing that Lem was in fact a committee and not a person. Read the letter here: http://english.lem.pl/faq#P.K.Dick
[2]: http://dpuadweb.depauw.edu/icronay_web/lem%20stapledon.html