If you know what the good stuff is, however, such as the most valuable Depression glass colors to search for, then you can peruse those sales and stores with a plan in mind.

Before you hit the flea market or thrift store, bone up on all you need to know about Depression-era glass including colors ...

Uranium glass is quite valuable, but you'll need to be careful of one health hazard when thrift shopping for this glass. Because it glows under a black light, you might see it displayed that way.