According to 6th Edition Blue Book of Modern BP Arms (2009) a 2nd Gen 1860 Army is valued at:
100% - $775; 98% - $550; 90% - $325; 80% - $250
Take $75 to $125 off for damaged or missing box & papers.
There's a NIB 1860 on GB with a damaged box & missing papers that has been there a while with opening bid price of $600. No one seems to want it at that price presently. They've been going for less.
I bought an 1860 Fluted Cylinder, no box in real good condition for 345.00 at a gunshow a coupla months ago.
Guy was selling it at a reduced price because he could not get the barrel off. Every second or third gen I have ever handled has a very tight barrel to arbor fit. I think it may be a sign that the barrel has not been removed very often. IE the pistol has had little use. (Or a lot of use and no cleaning)
I got it home and used WD40 to loosen it up. It is fine now.