Dont do it, I got called from a place called Canadian Auto Finder and they said the same thing, except it was a little cheaper $150, they gauranteed that they would find someone to buy or I would get my money back after 90 days. Took about 6 months to finally get my money after I called the BB and the media.
Never got a call on my vehicle in the first 3 months, but I still get calls almost a year later (they keep vehicles on thier website to make sure that they have an inventory), even though I told them many times to take my vehicle off.
List your car for free on Kijiji, I got more calls there then I did on autotrader, and I sold it a week after listing.
Here is a thread I started awhile back about this
http://forum.calgarypuck.com/showthread.php?t=39945