My two favorite lenses (both for their sharpness and for the wonderful way they throw all the boring stuff out of focus at maximum aperture are the Nikkor 85mm f/1.4 and the 200mm f/2. Nikon has made versions of the 85 back into the 1970's, so you ought to be able to find a well used one for very little money. AF will of course cost you more. The 200 is a newer lens. Maybe you could find a used one for $1000.