I paid the $70 for the listing that keeps it up until it sells. I just sold my wifes old Audi A4 on it (also listed here in the vehicles section), it was up for about 3 weeks, then all of a sudden I was getting calls left and right, and once the calls came in, took 2 days to make it final.
Had the same experience two years ago with an Xterra. Sat on Autotrader about 2 weeks, then calls started coming in, and it was gone within a week.
All the ones Ive sold on Autotrader I have gotten within $500 what I was asking for. The two I sold on Craigslist were always a pain to meet up with the people, and its as if they are expecting to make a steal with you. Too many random TXT messages with Craigslist too with messages like "Ill give you $2000 cash right now" when youre asking $6k. Annoying.