Constellation Piepan gold 60s

Hi everyone,
I'm looking at the watch listed below. The seller is the first owner, service history is unknown and there are no images of the inside.

I know there is huge risk attached to this, but I'd still wanted to ask your views on the photos that are shared below. What would you find a fair price, assuming the watch is running fine, but that it will need a good service? (ofcourse there's the risk that it's Franken on the inside, but it might be a risk I'm willing to take)

Thanks in advance!

Does the seller still have the bezel that has come off? If not you should either reconsider purchasing or at least lower your offer substantially. Wonderful looking watch besides that.

Ah I feel a bit stupid now! It did feel something was 'missing' but couldn't put my finger on it. For the rest the dial looks beautiful indeed.