Like all books ever published, Leroy and the Old Man by W.E. Butterworth should be available on the used market. If you're lucky, it hasn't become a collector's item (with the corresponding price inflation).
There are a number of useful sources for used books on the net,
including:
Bookfinder | Search Bookfinder, a meta-searcher for used books |
Advanced Book Exchange | |
Amazon.com | Search for author |