I feel for those of you who have been scammed. Hopefully, karma plays out for them, and perhaps you'll have a 'win' in the near future that makes up for it.
I'm almost to the point of quoting any online used buy/sell activity.
I've bought/sold bike stuff, and a few other categories of items, on kijiji for 10-15 years. Pre-covid, didn't do too bad. Most items would go in 1-2 weeks, a lot of views, responses were generally positive even if a sale didn't occur. Most who did respond, got back to you even if they decided to pass on the item. Likewise, I would message on things I was interested in, and most sellers were respectful and good to deal with. During covid, selling was a piece of cake. Now, sigh, about 90% of the interactions I've had are with pinheads. People who in one minute seem so interested "I can be there today between 3-4pm", and when you say you're working, how about after dinner, you never here another word from them (this has happened with 8 out of the last 10 interactions). I've had items listed for months with no activity. I may donate a bunch of things to a bike collective or not-for-profit and hopefully the old parts (mainly saddles and stems) will go to a good home. I'm a really positive person, but it's hard to be positive with a lot the online activity these days (and these are not scammers, just, pinheads!).
Buy/Sell looks great on this site. I'm in Canada though so that's a bit of a challenge (though I do use cross border pick up site, and it works fine, both directions), plus I'm at my budget for spending on bike things, for now, and I have most of what I want.