I would first attempt to date the piece by ID-ing the tughra. The image in the center of the dark circle is called a tughra; a calligraphic monogram of the sultan's signature. There were 36 sultans but I can't associate your piece's tughra with any of the 36 sultan's tughra. Your eyes may be better than mine.
It’s going to be tough to put a value to that, except to say it’s not ancient and probably not particularly valuable. It also looks to be in poor condition.
The overall design is based on the Ottoman Empire coat of arms in the version adopted in 1882 under Abdul Hamid II. The Empire was dissolved in 1922, with the Sultanate being abolished on 1st November that year. So that’s your possible date range, but be aware that the imagery continued to be copied for a while after that for reasons of nostalgia.
As Don says, the tughra doesn’t appear to be for any of the Sultans [better pictures at the Wiki link below] but, as the Empire collapsed, people began using calligraphic tughra representations of their own names… including dignitary, personal and company names. My guess is it's one of those and likely dates from the 1920s or later.
I think that's just the usual 'motto' on the crescent within the coat of arms, Don. It should read: "Relying on Divine success, the King of the Sublime Ottoman State" in Arabic.
I don't see the legend in the crescent as reading: المستند بالتوفيقات الربانية ملك الدولة العلية العثمانية. Nor does the tughra exactly represent a specific sultan. But I am open to the notion that both the teghra and the reading within the crescent were intended to imitate the Royal Coat of Arms.
Don in SoCal.