With that said for a modified car there is really no way to tell the price, it's only what someone will pay for it, for all we known the OP will find a buyer who is looking for the exact mods that the car already has done and will get a sweet deal.
But, bluebook is a tool made for dealers to make the most amount of money from trades and used car sales.
There is no definitive tool out there for true market value aside from manheim and other auction sites.
The closes value +/- 1k is this site
Used Car Pricing for 2009 Nissan 370Z Coupe | Clearbook by TrueCar
some argue the modding detracts value, but that's just a matter of opinion.
OP don't listen to the haters, you will find the right buyer - just need time, unfortunately winter is the worst time to sell a niche sports car, especially being a niche within a niche.