Yes there are classifieds here, there are facebook groups (although I think many of them are geared to specialized gear) and I guess Ebay is an option although again, I'm not sure how much "used"
mods get sold on there, if they aren't super high end, etc.
If you can get verified, that may be an option. There is also the "PIF thread," where you can offer your gear to those who may need it etc. Also, I believe most Veteran Centers will accept donations of vape gear (which means you can write off the donation in your taxes, if all else fails and etc.)
Good luck and welcome
Anna