Best wide angle zoom for under 800$?

I have the these lenses:
35mm
18-105

I take lots of landscape and sunset photos and my budget is 800$ I have the Nikon D7000. What lens will I get the most bang for my buck?

Add another hundred bucks and get a Nikkor 10-24mm.
http://www.adorama.com/...4AFSU.html

Failing that, consider the Tokina 11-16mm/2.8 (limited zoom range but very sharp) or the Sigma 10-20mm f/4-5.6.In case of the Sigma there's also a constant f/3.5 version, but the variable aperture version is both cheaper and better, surprisingly.

The Tokina 11-16 is a super sharp wide angle lens is one that I will vouch for

others include the Nikkor 12-24 and 10-24

http://www.kenrockwell.com/...1-16mm.htm
http://www.kenrockwell.com/...0-24mm.htm