It's not worth $100 IMO.
$50 tops.
For an upright road bike it's okay, amusing the frame isn't cracked and none of the major parts damaged or badly worn, and there's no warranty there of course. So the real question with a used bike is "how much can you afford to lose".

-----

I don't know why people do this, perhaps they are hoping for the one person who has been looking for such a thing for months/years, that the price will be paid.

I have seen the same phenomenon for other non-bicycle stuff as well. Every now and then there's a thread on cloudynights.com (amateur astronomy/telescopes) making fun of such ads.

People think that the value of a junk department-store telescope rises dramatically just because they let it sit unused for a couple years, and they "have the original box and all accessories". The telescope they paid $300 for, and then try to sell it on Craigslist for 2-3-4X as much, when the nearly identical current version of the same telescope sells for $130 at Wal-mart.com.
~