You asked
Is the fujifilm xf 27mm f 2 8 r wr worth buying used?
Yes, I think it's a good candidate for buying used. A 27mm f/2.8 prime on APS-C frames like about 40mm on full frame, which suits everyday street, travel and portrait work, and the lens is small and autofocuses. I don't have price data, so check what sellers are asking against what you'd pay new.
It also fits a lot of Fujifilm X bodies, from the Fujifilm X-E2 and Fujifilm X-T10 to the Fujifilm X-Pro2. That means you can pair it with an older body and still have a complete kit. The lens page lists every camera it works with.
When you buy used, budget for a new genuine battery, since old ones lose capacity. For more on buying second-hand, see buying used.
Written by Claude from this site's pages.