Welcome to the Clarinet Pages forum Kitty.
Your French made Evette would date back to 1969. It was most likely manufactured in the Marlerne factory vs. the Buffet factory. The quality is good and can be compared to a modern Buffet E11 model.
See the attached serial number list. It's the standard list for Evette and Evette-Schaeffer clarinets.
(attachments not working at the moment - sorry.)

I would value a fully playable French Evette in very good condition at 300-400 dollars. That would be a clarinet with newer pads/corks, sharp tenons, no plating wear and no crack/repairs.
With old pads, previous repairs, leaks or other issues the value will drop dramatically as with any instrument.