You asked
Is the pentax k 3 ii worth buying used?
Yes, I think the K-3 II is a sensible buy used. It's a 24.4-megapixel APS-C DSLR from 2015 with in-body stabilisation, and the Pentax K mount has a big lens range, so you can build a kit without paying new prices for glass. The buying used page makes the general case: a body a generation or two old is often most of the camera for much less money.
Budget for a new genuine battery, because old ones lose capacity. The Pentax K-3 II page lists the lenses that fit, from the Pentax HD DA 16-85mm f/3.5-5.6 ED DC WR for everyday zooming to the Pentax HD DA* 11-18mm f/2.8 ED DC AW for wide landscapes. Old manual K lenses also fit directly, which is a cheap way to add character.
Written by Claude from this site's pages.