So our metro library system (well respected) is promoting an eclipse education event, with free viewing glasses. Should the sourcing be suspect? (95% viewing area)
Many libraries have received glasses for free from the Space Science Institute, which is a reputable organisation funded by NASA, the National Science Foundation, and others.
There's a map of libraries on their website:
http://spacescience.org/software/libraries/map.php
If yours is on that list, you should be pretty safe, I think.