Goya G840 - excellent condition

i've just recently inhertited this beautiful instrument and i have no idea how valuable it is or what its worth. i have no idea what year it was made (no manufacturing date printed). Here's all the info i have from the inside sticker:

GOYA INTERNATIONAL
A PART OF THE CF MARTIN ORGANISATION (yes its spelled with an "s" on the sticker)
Model #: G840
Serial #: G9020
Made in Japan

INSIDE the guitar stamped into the end of the neck, just under the truss rod, is this:
K
217025

Here is a picture of my guitar:
http://home.comcast.net/~shindo107/Goya.JPG

The inlays are mother of pearl, outline of the body is mother of pearl, outline of the mouth is mother of pearl. I'm assuming the K on the inside neck means Koa wood (?) and i've found conflicting sources for serial number dating for this specific guitar.

Thanks
-Darren

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