I have personally picked up two from Craigslist. One was $450. Other was $200. Not a typo. Both were screaming deals. I have one, and my dad has the other.
I would wager the norm is more along what Barney posted, $600-1200.
Assuming all the spring jacks and top links aren't bent and good working order, at most you'll spend $75 in spare parts/spring bar bushings. Unless you have to get a new stinger, that is.
A friend of mine just picked one up for $800 off craigslist with some extras and such. It was in pretty good shape and had the cover as well.
That's three Hensley's within a 50 mile radius of my location. Still can't believe we've gotten that lucky.