You asked
Is the 7artisans m 28mm f 1 4 worth buying used?
I can't tell you whether it's a good price, because I don't list prices, but the lens itself is a fair candidate for buying used. The 7Artisans M 28mm f/1.4 is a manual-focus prime for full frame, and it only fits Leica M mount bodies, so check that your camera is one of them before you go looking. It's a sensible fit if you already shoot a Leica M and want a wide, fast prime.
If you're weighing up used gear in general, buying used explains why the secondhand market is one of the best ways to afford good kit. You can see every compatible body on the 7Artisans M 28mm f/1.4 page.
Written by Claude from this site's pages.