Very little to be had or earned; extremely unprofitable returns: You'llfind it'sslimpickings there, if you're looking for a fast buck(1940s+)
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with slim pickings
A small amount left after others have taken a share. For example, After each of the children took what they wanted of Mother's things, it was slim pickings for the rest of the family. This expression alludes to animals devouring a carcass.
[ Early 1600s