I originally picked up this Nikon 50mm F/1.8 E Series Pancake lens for use with the new Sony NEX-7, but I thought I would remind others that are just starting out in DSLR video, that these very inexpensive lenses can be used with your Canon DSLR cameras as well.
One of the first lenses most people suggest to others (if they are strapped on budget) is the Canon 50mm F/1.8 (found here). It's a fast and sharp prime lens that runs around $120 dollars, and the images will blow away the basic 18-55mm kit lens. The main complaint on this lens is the plastic build quality. If you don't require the autofocus feature, you can shop for older manual lenses which are better built with a smoother focus ring for video.
Lately i've been seeing a trend with inflating prices on older lenses. I'm constantly being outbid on many of the faster (vintage) prime lenses. Today, there are more mirrorless type cameras that can use these lenses, and more lens adapters available to mate the older Minolta, Pentax, Nikon, Canon, etc. lenses. If you have any collected from an old stash, keep them close. They have more value today, than they did just a few years ago.
Canon 5D Mark II + Nikon 50mm F/1.8 E Series Lens
If you're just starting out, these Nikon 50mm F/1.8 pancake lenses may not be the sharpest of older manual lenses, but I like the compact size, wide aperture, and the out of focus backgrounds. You can find many of them still for under $75 dollars (click here).
Nikon 50mm F/1.8 E Series Manual Aperture Manual Focus Lens
and 
will especially be of interest to existing mirrorless interchangeable lens camera shooters. And unlike the first introduction of NEX cameras, these should both provide you with FULL MANUAL VIDEO controls. Lots of new updates, features, and with cheaper pricing should give Sony a good market share this year. 
