Hi !
Computar lenses where on the market for a brief period of time (in darkroom, not in CCTV) And the 55 being top of the range, was at a high price tag. Add to this that people tend to buy by reputation and not by technical qualities, and you've small volume sales. Plus the guy who owns one _knows_ he has a gem, so the second hand marked is really tiny. And at a premium price...
If you can find a 105 mm APO nikkor for my enlarger.....