More than one photo and view is needed. But, ultimately, the value will be up to you and up to whomever wants to buy it as a musical instrument.
Looks like it was made for presentation or as a souvenir. About 40 inches long? Maybe someone’s birthday or anniversary?
I wouldn't assume October 8, 1985 is the date of manufacture. It could be the name of something. A school, for instance. Debora
According to google "A typical Marimba cost is between $10,000 and $20,000" That doesn't make sense? Mikey
That would be a darn fancy marimba....my brother made a very big one once (it was approximately the size of a VW beetle, in two parts for transportation), and sold it to the Crusaders drill team in Seattle, who used it on a flat-bed truck in parades....but it was not for anything near that. His typical Zimbabwe-style marimbas were more like $500 at most...not enough to actually pay him for the time it took to make them, so he doesn't do it anymore. But, I can't even be sure this is a marimba without more pics.