Schwing's 2006 Catalog of Firearms lists them. The standard model in VG $1,500, with the folder in VG at $4,250. However, I think this is one of those items where these figures don't mean a lot. He does have pictures of the engraving patterns used.

Greg Martin is putting an estimate of $40,000 on Pat Garrett's Burgess.

Here is a folder that sold recently, no engraving:
http://www.gunbroker.com/Auction/ViewItem.asp?Item=79230493

Some pictures, not much information.
http://www.shootingbums.org/hvr/burgess.html

Unless the gun is a total wreck do not refurbish it. You will only hurt the collector value.

Pete