I find Pyrex bowls and covered dishes at almost every estate sale I attend. There are probably two reasons for this: one, Pyrex containers were popular with homemakers throughout most of the 20th century; and 2) they tend to last a long time.
I can't buy all of the Pyrex bowls I see, of course, but I have been able to collect quite a few of them. They don't just sit on my shelves -- I use them almost every day.
I also find Pyrex ads in vintage magazines at estate sales.
Here's a website devoted to Pyrex glass patterns:
The Corning Museum of Glass exhibition on historic Pyrex runs June 6, 2015 through March 17, 2016.
The Country Living article on Pyrex is here:
You can find photographs and links to other blogs about Pyrex bowls and dishes on Pinterest: