That's a pretty limited budget for a lens. Is that $200 total, or $200 per lens (assuming you're looking for more than one)?
Regardless, you'll probably want to look into used primes. They will get you the best bang for your buck, and with an affordable adapter you're not restricted to Canon mount lenses. Common focal lengths are 24,28,35,50, and 85.
If you look at zoom lenses, you'll want to get one with a constant aperture. There's likely nothing that fits your budget though, even in the used market. You could certainly get away with a cheaper variable aperture lens, but it's just not ideal for video.