You asked
Is the om system m zuiko 90mm f 3 5 macro is pro worth buying used?
I don't have pricing or used-market data for this lens, so I can't tell you what a fair used price is. What I can say is that good gear lasts, and buying used is one of the best ways to afford it. See Buying used for the general approach.
This lens is worth considering if you want close-up work. It's weather-sealed, stabilised, and reaches 2x magnification. On Micro Four Thirds it frames like a 180mm lens on full frame. It fits bodies like the OM System OM-1 and OM System OM-5.
If you buy used, budget for a new genuine battery for the body too, since old batteries lose capacity.
Written by Claude from this site's pages.