The best lens imo that I have used for filming is 35 1.4. Colors are on point, super sharp at about f/2.0, awesome dof for interview shots, nice weight, and it's pretty much bombproof. Even though they are a little more than your price range, look on craigslist; u can find them from about 900-1000.
Also because of the great reviews plastered all over the internet I recently purchased the Tokina 11-16 and I was pretty amazed at how well it came out in film, not too much distortion at all and I would definitely recommend it. Here is a short clip that was filmed with the tokina
http://www.vimeo.com/21906133 .
One way to figure out what lens will work best for you is by renting them, that's what I did. I have a store in Seattle that does but if you don't live there I would check out borrowlenses.com. I have used them before and there service nothing short of amazing. They have anything you could think of for dslr filming to try, from glidecams to all of the high end canon lenses. They even have some of the nicer ziess lenses as well which are pretty sick. They also have sales on used gear and if you get on there email list they often send out coupons for cheaper rentals-also check there twitter for coupon codes as well.