Inexpensive wholesale beer glasses?
Believe it or not - I'd say hit the 99 cent store. They often have Libby glasses there (and that's what you often get when you rent, as they are so sturdy) and I've seen the classic "pint glass" there.
You can also order by the case from Dollar Tree and pick up at the store. Good Anchor Hocking Glasses for cheap!
Check out this previous thread: http://chowhound.chow.com/topics/627025
There are suggestions for stores as well as a link to reliablepaper.com which seems to have good prices.
You may want to consider rental places, too. I used this place for tables, and they were good: