Tamura worth?

[gardenz]

I have a 1974 Tamura P-100 classical made by Hiroshi Tamura and was wondering how much it was worth. Based on what research I could find, the Tamura brothers were both luthiers in Japan who started building guitars in the 1950's. I'm reading that the model number multiplied by 10 signified the suggested retail price at the time, meaning the P-60 sold for $600, P-150 for $1500, etc. Supposedly they also had a flamenco line of guitars. Anyone familiar with this guitar and have any ideas what a P-100 in good condition might be worth?