I don't think it is an unreasonable price... BUT it is 15 years old and M35's can be had for less than $13k.
Not saying it would be a better deal, but generally people want the newer model if they are the same price.
I guess it is the usual story - S1 prices drop when S2 is available, S2 prices drop when NM35 becomes available, NM35 prices drop when PM35 becomes available.
What I do think is unreasonable is that properly installed mods don't increase the value of a car over here like they do in Japan.