Cranks generally go anywhere between $500-800 in used/unknown condition, freshly pulled from the block.
Ones that have been checked or worked over by a competent machine shop, with supporting paperwork demand more depending on the extent of work done.
There are custom cranks coming to market that have put a cap on the price of tired LD cranks.
The glow plugs and fuel system seem to always be in demand by LD enthusiasts, though I can't begin to accurately give prices. NissanDiesel forums will be your best resource there.
Other parts, including the intake manifold and oil cooler setup have occasionally been sought by people looking to do something out of the ordinary... Generally speaking these stay around the $100 mark unless they are in especially good condition.
I'm looking for a extended capacity rear sump oil pan from the industrial variant (or Cedric i believe). The few I've found are also around the $100 mark.
I believe someone was looking for a block a while back...