I miss the popularity of Craigslist for selling vehicles for these reasons. Used to be I'd get 3-4 responses and usually the first one serious enough to come check out the car would buy it.
Now on FB it's 50-100 messages, 90% of those are "is this available" or "what's the lowest you'll take" (to which I usually ask "what is the highest you'll pay?")
Out of hundreds of messages total, not a single person that actually bought a vehicle from me on FB discussed price before coming to see it.