If you can get any of The Best Of......... series of Ballantine paperbacks they are worth getting, I think they were published in the seventies and eighties so only available on the second hand market.
Apart from the good cover art they usually have a good selection of the authors work.
Not sure how many there are, think I've got them all, there must be eighteen or more in the series:
Paul Anderson, Henry Kuttner, C.L.Moore, C.M.Kornbluth, Phillip K. Dick, Cordwainer Smith, Frederic Brown, Edmund Hamilton, Fritz Lieber, Eric Frank Russell, Murray Lienster, Robert Bloch, to name but a few off the top of my old and balding head!