[JohnnyZ]

I'm thinking more along the lines of the Betsy & Tacy books (my big honkin' Borders only had one copy of one of them -- remember the line from "You've Got Mail" where the big box bookstore clerk had never heard of Betsy/Tacy and Meg Ryan has to clue them in?), All-of-a-Kind Family, the E. Nesbit Railway Children/Five Children and It/etc books. Came prepared with a list in my head of 5-10 titles for my friend's daughter and had to settle for Walter Farley and the Witch of Blackbird Pond.

Graham Greene's children's books are out of print, as far as I can tell. Pearl S. Buck's children's classic The Chinese Children Next Door is out of print.

[GOP Jedi]

Abebooks.com (http://www.abebooks.com) is a great resource for OOP books. For example:
http://dogbert.abebooks.com/servlet/SearchResults?an=Maud+Hart+Lovelace&y=11&sortby=5&x=60