You asked
Is the sigma 300 600mm f 4 dg os sports worth buying used?
Yes, I think it's a good candidate for buying used. Long lenses hold their value well, and secondhand is where the real savings are, which matters with a lens this size. Check the autofocus and stabilisation before you pay, and buy from a seller you trust.
The Sigma 300-600mm f/4 DG OS Sports is a constant f/4 zoom with stabilisation, made for full-frame bodies in Sony E or L-Mount. If you shoot wildlife or sport and want that reach without a big upfront bill, it's a strong pick. For the approach, see buying used, and for where this lens fits, see wildlife and sport.
Written by Claude from this site's pages.