In article <4fte9b$qor@hawk.pix.za>, cognad@pixie.co.za says...

>Does anyone have an opinion on the following equipment:
>* Nikkor 300 f2.8 & 400 f2.8 (how does it compare with the 500 f4.)
>* Nikkor 105 f2.8 (micro)
>What are the current market prices for these items?

Once you get to the big, expensive ED Nikkors, it doesn't seem to
matter much which you use - they are all fine lenses, and probably
pretty hard to tell apart in optical quality. As for the 105mm
macro's, there are some variations. You may want to check this out:

D. Ruether's "SUBJECTIVE Lens Evaluations (Mostly Nikkors)",
which includes a listing of all Nikon SLR lenses ever made (with a
subjective evaluation of many of them, a general description of Nikkor
lens performance characteristics by lens-type groups, and comments on
particular lenses when the general descriptions plus the subjective
evaluation numbers are not sufficient to describe performance),
can be found at these sites:
-- Jan-jaap Aue: (nice text format)
http://www.phys.rug.nl/mk/people/aue/nikon/david.html
-- Bo-Ming Tong: (go to end of long article, plain text format)
http://www.cs.arizona.edu/people/bmtong/photo/nikon.faq
-- Quang-Tuan Luong: (plain text format)
http://robotics.eecs.berkeley.edu/~qtluong/photography/35mm/nikon-neuman
-- Niklas Nikitin: (nice table format)
http://www.cs.hks.se/~nicke/private/photo/david.html

As for prices, check out the ads in Shutterbug magazine.
Hope This Helps