thanks for all advice.
as for Hagerty value, not really apply to many case, and way off by many cases.
this is one case, I still don't think a 1986 930 will sell for average 195k.
https://www.hagerty.com/apps/valuationtools/1986-Porsche-911-Turbo_930
however some cases they might be much lower than actual car worth,
plus, they were way off for 911 prices for many years, and suddenly jump very high...