Originally Posted by Scott Dodge

17mm isn't that wide... remember the crop factor.

I'm pretty much in the same boat, but I have Nikon stuff. The 10-20 is a great lens - I've seen tons of great results from it. Haven't personally used one, though.

I'm saving up for the Tokina 11-16mm f/2.8, which is ~$60 more than the sigma. It's supposed to be the best WA for DX sensors. Not sure if they are releasing it for pentax.

The fisheye is a cool effect, but I could imagine it getting old pretty quickly.