You asked
Is the canon ts e 135mm f 4l macro worth buying used?
I'd say it's worth considering used, as long as you're happy focusing by hand. The buying used page makes the case that a used market is one of the best ways to afford good gear, and this is a manual focus macro, so there's no autofocus system to worry about.
It's a full frame lens, so the Canon EOS 5D Mark IV or the Canon EOS 6D Mark II are the natural partners. On an APS-C body like the Canon EOS 90D, it frames like about 216mm, which gives you good reach for small subjects.
Check the optics and the mount carefully before you buy, since you can't test autofocus to reveal faults.
Written by Claude from this site's pages.