You asked
Is the yongnuo yn17mm f 1 7m worth buying used?
The site's view on used gear is simple: cameras and lenses last, and buying used is one of the best ways to afford good kit. I'd say the same here, so if the 17mm f/1.7 suits your shooting, a used copy is a sensible way to get it.
It's a Micro Four Thirds prime with autofocus, and at f/1.7 it's bright enough for indoor and low-light work. It isn't stabilised, so it's worth knowing that before you buy. Check that the focus works properly and that the glass is clean and free of marks. Its Micro Four Thirds mount takes a wide range of bodies, so you'll have plenty of choice there. If you're still deciding what to buy, buying used covers what to look for.
Written by Claude from this site's pages.