Last week I found an Ace F-322 edition of Three Against the Witch World, which was the first publication of the book. While I already had a slightly later copy with the exact same cover, except Ace number and price, I picked it up because it was a first edition, and it was a great deal.
The book can also be found in the Ace Letter section and in the Jack Gaughan section. I also fixed the date of the other copy under the Jack Gaughan section; I had it as a 1965 edition and it was really a 1969 edition.