Best Nikon/Canon lenses with these features?

I'm looking to purchase an affordable wide angle or fisheye lens some time in the near future, and I wanted some opinions as to which I should get. I was originally going to go with a 35mm or 50mm prime and just get a cheap $50 adapter/lens, but I hear those are very unsatisfactory when it comes to quality. Here's what I'm looking for:

-The lens will be mounted onto either a Canon T4i or a Nikon d5100 (You may leave suggestions for either)
-I'm not into an extreme fisheye look (take the Rokinon 8mm 2.8 or the Nikkor 10.5mm 2.8 for example, that's a bit too much of the fisheye effect for me), but I love those really wide angles and a perhaps touch of the fisheye look
-Auto-focus is a feature I'd really love to see the lens having, as I'm not the best with manual focus and I want this lens mainly for video taking (I LOVE the look of the Rokinon 14mm 2.8 but the downfall is that it's all manual, but still perhaps my best choice right now)
-But, I also want it to be affordable, I don't think I'm quite ready and willing to spend more than $500-600 on one lens
-I'm totally okay with prime lenses but in my dream world I'd love a zoom lens

Again, I wouldn't be surprised if there were lenses out there that met my wishes, but I could see those becoming very expensive very fast. But if you know of any lenses that meet even a few of the things I listed, it would be great if you could suggest them!

The Tokina 11-16mm f/2.8

it's a super well built lens with optics as good as Nikon and Canon. The new version will autofocus on Nikon entry level DSLRs (the previous version did not).It will also autofocus on Canon DSLRs

as to manual focus, with a wide angle lens, it is super easy. It's actually hard to not be in focus when you go that wide.

on the flipside, the lens does cost $700 which is a bit more than your $600 budget, but in my opinion, it is well worth it.