It comes down to supply and demand. Although the numbers are fewer for the R35 - the owners are adding mods at every corner. Just reference any of the GTR sites and see the parts available and the steep prices and you’ll quickly see that the aftermarket is bursting with parts for a limited production vehicle.
Different market fundamentals for the 240’s vs GTR’s.
If there was enough interest we could look into the KA/SR markets down the road.