At first glance 2000 frames seems like a window-shopper's dream. Sadly many of those frames are simply the same one offered in multiple colors (and thus listed multiple times: once for each color). This actually makes the browsing experience a little more frustrating for some.
The good news? Goggles4u has a heavy emphasis on frames for under $10. Almost half the frames fit into that category. In other words: this is not one of the places where you get a really small selection of "cheap" frames with the intent being to up-sell/bait-and-switch you. They're completely oriented towards the budget glasses market.
The frames themselves start at $0: a great price at first glance. That does not include lenses though; basic lenses add $6.94. If you're unlucky enough to hit a time when they do not have $0 frames (they tend to change their pricing around regularly), you might be looking at up to $5 more. Either way it's almost always possible to get something shipped to your door for somewhere between $10-20 all-told. And that's not bad.
Goggles4u websiteWith over 2000 frame ranging from $6.95-45.95: Zenni has a selection for numerous price points in the budget range.
Realistically you're looking at about 50 frames in the <$10 range and 300-400 in the <$20 range whether browsing the Men's or Women's categories. Kids frames have a lower selection (about 1/5 of the offerings of either adult selection at any price point).
The frames are often offered in more than 1 color and do come with free single-vision lenses. Generally speaking: Zenni keeps a healthy selection for every price point.
Zenni Optical websiteAbout 50 frames under $10 can be found with a few hundred more in the under-$20 range. They do list duplicates when multiple colors are available but when you choose a frame you can often select the alternate colors that way as well. They top out at just under $50.
Single vision lenses come free with the frames.
EyeBuyDirect website<< These aren't the cheap glasses you're looking for *hand-wave* (take me back to other cheap glasses options)
Some data might be wrong on this site. Do not take it at face value. Do your own research to verify the claims here.