I more see the opposite in my area -- people listing used items for sale for more than it would cost me to buy the item brand new shipped to my house. This is particularly the case with electronics. Idiots remember that they paid $400 for a TV 5 years ago, and figure it ought to be worth at least $250 now, only they can't bother to do a simple search on Walmart/Amazon/Best Buy to see someone could get a better brand new TV for $150. I see it for so much stuff, I don't even bother trying to use Craiglist in my area, because even if you find something you actually need, and they're the 1 person in 10 who actually is asking for a reasonable price for their used item, and they're the 1-in-5 who actually respond to their own ad, they'll probably stand you up when you go to make the deal.
CL does seem to be a very localized thing. In NY, You always had to price in some negotiation, b/c no one ever buys at asking price. And some people are downright rude - after posting a very nice glass table & 4 chair set in pristine condition for $150, some jerk e-mailed me with the following: "I have $25 for you, make it so!"
Out here in TX, I'm shocked at how rare it is for folks to negotiate - they come prepared to pay asking price. But they are so much more lax in their follow-through. Missed appointments, having to work around their schedules, etc - probably the most infuriating part about selling on CL around here.
You will always have people who just think their crap is worth gold when they need to sell. They are the same ones who think your crap is worth $1 when they need to buy. My strategy is simple, I'm very honest about the condition of the item, and I take good care of my stuff. Before I post, I check and see what the competition is selling similar items for, and I price mine competitively, usually a little below the competition. Most of the stuff is gone in 24 hours, with multiple back-ups in place for the no-shows.