What lens are best for me?

I have a nikon D90 with currently a nikkor af-s dx 18-105 lens (part of the kit) and i want to get new lens. I'm really into landscape and street phtography (sometimes protraits but lets leave this out for now). I was thinking of getting a wide lens (maybe prime but not sure). What i want to ask is if i would notice any difference between my 18-105 and an 18-24 maybe or other wide lenses that include the focal length i already have. Is it a good idea to buy smaller focal lengths like 10mm? What are my best options? I'm an amateur not a pro and my budget is around 200-250.

Jaja

To get a wide angle image that 'pops' you're going to want to go out to 10-12mm. But if you don't want to be forever changing lenses (and you would with say a 14mm manual Samyang or the excellent 11-16mm Tokina) then a 12-24 will be much better for you. There's no need to stick to the good but expensive own brand lenses when you can look at Tamron SP and Sigma. You can even buy used from reputable dealers.

Used 10-24mm Tamron in Nikon Mount

http://www.ebay.co.uk/...2576270768

Used Nikon:
http://www.wexphotographic.com/buy-used-nikon-12-24mm-f4-g-af-s-if-ed-dx-lens/p1621199?mkwid=szwyofrid_dc&pcrid=86900797139&kword=&match=&plid=&product=1621199

Used Sigma: 12-24

http://www.lcegroup.co.uk/Used/Sigma-12-24mm-EX-DG-HSM-F4.5-5.6_177078.html

The 18mm setting on your kit lens is excellent for the uses you cite. And you already own it.

A wide zoom might be you next step. Do you own a solid pro style tripod yet? And a remote shutter release. Both good things.

Your skills with lighting and composition will enhance ANY lens you buy.

Your goal seems to be to shoot stunning landscape photos

Your question seems to include information that should answer your question.

"i want to ask is if i would notice any difference between my 18-105 and an 18-24" 18 mm is the widest angle of view on both those lenses.

As mentioned, you will need a lens like the Tokina 11-17 mm to increase the field of view.

Here is a link that will help you visualize what different focal length lenses "see"

Image quality improves, the less zoom the lens has but if you get the 18-24, gain nothing in terms of focal length. A better option would be to buy a lens with a different focal length than what you already have. Try something like the Tokina 11-16mmor the Rokinon 14mm f/2.8. Beware though that below 12mm is fisheye. The distortion level it brings won't look good with landscapes.

Whether you'd see a difference depends upon the lenses, of course, but also your intended use. Yes, if you upgraded to a high-end glass, you would definitely see a difference when comparing full-res images on your computer at 100%. However, when comparing images on facebook, the differences will moot because of how facebook shrinks and compresses the image file when you upload.

To see how much sharper lenses are, go to photozone.de which uses numbers in their sharpness charts. This makes it very easy to see just how much sharper one lens is vs another.