Here's a deal on a lens that I highly recommend for such cameras with a crop - The Rokinon 7.5mm Fisheye. Typically this lens will run for $299 dollars and you can see that here (via Amazon) and also here (via B&H).
Every now and then the DSLR market goes wild when they can score a $500 dollar Rokinon 35mm F/1.4 lens for $350 dollars on a Daily Deal. I've seen these things sell out in literally minutes for that price. Well, If you didn't know this already, these lenses can be found under different names such as Rokinon, Samyang, and Bower.
So, If you've been specifically only searching for 'Samyang' or 'Rokinon', you'll find this popular 35mm F/1.4 running for around $450-$500 dollars (as seen here), but right now the 'Bower' name brand, available in Canon, Nikon, Sony/Minolta, and Olympus Four Thirds mount, is offering this same lens on sale (sale ends in a week or while supplies last) for just $379 (found here).
Don't forget that these lenses are quickly re-colored and re-branded under names like Bower, Rokinon, Vivitar. So when those names become available, you'll also be able to find similar ones via Amazon below.
I'm still set on getting some type of Tilt Shift lens (eventually), but if you just want to experiment putting some videos together you can do this without an actual Tilt Shift lens. One of the popular tricks is to shoot far. Really far. Here's an example of a Tilt Shift video I posted that used post processing software to create the effect: http://cheesycam.com/tilt-shift-without-the-tilt-shift-lens/
Sounds like a monster telescope, but mirror lenses use a technique to multiply the image inside a small form factor. The cons to using this technique is some softness and loss of light and the best of the best Mirror lenses at 500mm might be about F/6.3. The pros are you're able to get a crazy distance in a lightweight lens for super cheap. These lenses are often rebranded so Samyang is just one name. You can also find them in Rokinon, Vivitar, and Bower. Imagine using this lens on a GH2 or T3i with new Cropped modes - Crazy far!
Samyang, Rokinon, Bower, or Vivitar. It's believed they are all the same lens, with a slightly modified exterior and sold under various brands. Who knows what these lenses are being sold as, but then again you might not even care. Rumor mill has it that these lenses are being made out of Korea providing images that can be sharp as Nikon. Of course there's no auto focus features, so with zero electronics on this Manual Focus prime lens it's sold cheaper and can be made to be tack sharp.
The 85mm F/1.4 is an excellent lens for low light situations, and at the focal length to provide you with that crazy DOF portrait look. The lens may only have been introduced a few years ago, but the Internet is littered with tests/reviews/samples. From Flickr, Vimeo, YouTube, web blogs, and camera forums it's been tried and tested to be a solid performer. With manual only features it might also be an easier lens to pull focus with for full time Video shooters.
For Nikon shooters considering the Budget 85mm, the Samyang and Bower name is designed with an exterior of the traditional Black w/ Gold Highlights. For Canon shooters, the Vivitar branded lenses are designed in all black with a knock-off Canon-like Red Ring accent. For those who aren't quite into the exterior aesthetics, over at Amazon the 'Rokinon' name will drop the price down another $100 dollars. Not bad for the money considering several reviews tested it to be as sharp as Nikon, and another great option for shooters looking for a lens that works well in low light situations. Anyone out there rockin' one? Leave some comments....