One of Omega's bracelets that they sell for people to put on watches that didn't necessarily come with bracelets. As you can see, it doesn't fit that watch, but for some reason inexplicable to me, a lot of people don't seem to care!
https://www.omegawatches.com/en-us/watch-omega-de-ville-omega-md-111-0085
That link will tell you all anyone else could.
As for how much? That depends on you and how much you want it. Condition is very good. I wouldn't pay more than a thousand of whatever your currency units are, but half that wouldn't bother me, personally.