You asked
Is the ttartisan 50mm f 2 worth buying used?
Here is what the site says about that.
From TTArtisan 50mm f/2: TTArtisan 50mm f/2: A prime lens by TTArtisan for Full frame cameras, 50mm f/2. Specs - Maker: TTArtisan - Focal length: 50mm (prime) - Maximum aperture: f/2 - Made for: Full frame sensors - Mounts: Sony E, Fujifilm X, Nikon Z, Canon RF, L-Mount, Micro Four Thirds - Stabilised: no - Autofocus: no, manual focus What it frames like - On full frame (Sony E, Nikon Z, Canon RF, L-Mount): as marked, 50mm. ...
From Buying used: Buying used: Cameras and lenses are built to last, and many photographers upgrade often. That makes the used market one of the best ways to afford good gear. A body that's one or two generations old is often most of the camera for a fraction of the price.
Quoted from this site's pages.