I'm starting to research a next step... wide angle...

Nikon 12-24mm f/4.0 or some off brand like Sigma, or Tamron?
I'd be willing to look at off brand, if I had a convincing argument.

I'd like to hear from any Nikon wide angle users, as well as any with off brand lenses.

I have a 12-24 mm f/4.0 Tokina that I use on my D80 and D90 and I love it. There is a used one advertised on Craig list in Baton Rouge LA for $400. I was lucky, I paid $350 for mine . That's approximately 50% less than the Nikkor. I would guess the Nikkor would be even higher in Canada.I can send you the e-mail if you are interested.

Jack

The Pictureman

PS: Checkout my site on Photoblog or my website: jackthepictureman.com.

Thanks for your thoughts, @thepictureman. I'm looking at the options, goodness there are so many choices!
I've done some preliminary research.... I've got a side by side comparison here. I'd love to know if anyone else uses any of these. There is definitely a savings going with a non Nikon lens, but we're still talking a significant investment. I need to know it's worth it.

The list:

Nikon AF-S 12-24mm f/4.0 G IF-ED DX Nikkor Wide Angle Zoom
Sigma AF 10-20mm f/4-5.6 EX DC HSM Wide Angle Zoom
Sigma AF 8-16mm f/4-5.6 DC HSM
Tokina AT-X Pro 11-16mm f/2.8 DX
Tamron SP AF 10-24mm F/3.5-4.5 Di II

Not sure about the Sigma wide angles...I would say for sure that the Nikon 14-24mm is a ridiculously wonderful lens (don't own it but I have seen it in action and its photos), also I have heard good things about the Tokina 11-16mm. Sounds like you are doing the research, you really have to when it comes to dropping this kind of cash I just bought the Nikon 24-70mm 2.8 and I looked into the Sigma and Tamron versions, the Sigma was the lesser one, the Tamron decent but the Nikon is super nice even for its high asking price. So not sure about the wide angles but I think you get what you pay for. If I were to buy a wide angle for shooting landscapes, I'd want to get a sharp lens from corner to corner with little to no distortion. Happy hunting!

One other thing to think about...

Do you ever plan on moving to a full frame camera one day? If you do, you might want to consider buying full frame lenses that can easily transfer to a new camera. DX lenses do work on FX cameras I believe but in a crop mode.

I can vouch for the Sigma 10-20 even if I find 4-5,6 rather slow. The Tokina has a cult following although I haven't used it myself.