I bought my custom 24 on Facebook marketplace! I get almost all my music gear there. Pedals, amp, microphones, mic stands, pa speakers, a mixer, a drum kit, everything.
I've sold some pedals there with success.
It's like Craigslist but more active. I highly recommend it for finding deals, but as always make sure you know what you're doing so you don't get burned.
Edit to add: if I'm meeting someone in person, I'll pay without protection, the same as if I'm handing them cash. For that I use Venmo, PayPal friends and family, or zelle, and it's very helpful to have all 3.
If I'm ever having something shipped to me, like when buying on tgp, that's when I insist on PayPal goods and services or Venmo with purchase protection.