You asked
Is the sony a7 ii worth buying used?
Yes, I think the a7 II is worth buying used. It's a cheap way into stabilised full frame, with a 24.3-megapixel sensor and in-body stabilisation, so it works well with almost any lens. As buying used explains, a body a generation or two old often gives you most of the camera for much less.
Budget for a new genuine battery, since old ones lose capacity (see batteries). If you want a little more for the money, the Sony a7 III is the full-frame bargain of the used market and still very capable.
For an everyday kit, I'd pair the a7 II with the Sony FE 24-105mm f/4 G OSS for general shooting, or the Sigma 24-70mm f/2.8 DG DN Art if you want a faster zoom.
Written by Claude from this site's pages.