WCIF: well priced, new, DSLR lenses (particularly fisheye) (any brand) for Nikon D3100 or D90

Where’s the best place in Taipei to buy (new) lenses (particularly fisheye) for Nikon D3100 or D90? It can be Tamron, Nikon, or any other decent brand, at reasonable prices?

im a canon shooter so im not sure on best prices for nikon, but from what i’ve been hearing, camera street is the safest place to get legit new gear…its at ximen MRT station, exit 5…walk down until u hit hankou street…compare prices while ur there, some higher end lenses can differ as much as 2000NT