Remember also that some people list things for a higher price than they expect to get. I check craigslist a lot just out of curiosity. Some people have outrageously high prices and sometimes you see a good deal. If I were selling an used bike on craigslist, I wouldn't list it for 80% of original price, but if I only expected to get 50%, I might list for 60%. I've seen people list things for a high price and then a few days later you see the price creeping down.
Unrelated product, but I saw a guy list a saxophone for 650 and over the next week it creeped down to 300. That was a little depressing considering I have the same model.