Given how rare they are to find for sale these days, I'm not sure it's really that far from reality.
Although this 1 in Japan sold for around $26k AUD recently (not sure if reserve was met?)
https://page.auctions.yahoo.co.jp/jp/auction/b256041154
This project car was asking about $12k AUD. (price has gone silly after auction ended, not sure why?)
http://buyee.jp/item/yahoo/auction/j433722240
There is another in Adelaide here.
https://www.shannons.com.au/club/enthusiasts/GettingOlder/garage/1967-prince-skyline-s54be-3-gtb/
https://www.sau.com.au/forums/topic/469621-prince-gtb-value/
and I know of at least 1 other in a Barn in NSW...not sure what the owner would sell it for though!
If I didn't already have too many projects I'd get 1 myself.
They haven't reached the crazy price point of the KPGC10 or KGC10's and the mania around those. They seem to have been overlooked...