You asked
Is the sony a7r worth buying used?
Yes, I think the a7R is worth buying used, as long as you go in knowing what you're getting. It's a 2013 body with a 36.4-megapixel full frame sensor and no stabilisation in the body, so pair it with stabilised lenses if you shoot at slow shutter speeds. Its Sony E mount also gives you a huge range of lenses to choose from.
Used is where this camera makes the most sense. A body a generation or two old gives you most of the camera for much less money. Budget for a new genuine battery too, because old batteries lose capacity. The buying used guide covers the rest.
If you want a newer sensor for not much more thought, look at the Sony a7R III (42.4 megapixels) or the Sony a7R IV (61 megapixels).
Written by Claude from this site's pages.