Nikon 105mm Macro ...

It's not overpriced considering how good is it (in terms of both image and built quality).

Lens value is not determined by their age, but by their quality.

Consider how much expensive the Cosina-Voigtlander 125/2.5 Macro Apo-Lanthar is in the second-hand market. It's "old" (its design is 10+ years old), MF, no VR, no "nano". But it's a true apo macro lens, and it's "excellent". And better than any Micro-Nikkor, Sigma, Tamron, Tokina ...