To make the sale more valuable I would get a letter from the Cody Museum and contact David Kennedy http://www.bbhc.org/firearms/records.cfm
If the gun came from Hunter Arms with two sets of barrels I think that would make it worth more than if it was shipped back and had another set made for it at a later time. The letter should state whom the gun was sent to and what it came through with. I believe the letter cost $55.00.
Any older "elsie" especially with ejectors and an extra barrel is always a great find and in un-finished condition with no major faults could be worth $2500 up. It is like you said condition is everything. Good, sharp bright pictures, showing everything, is critical to selling, if the person cannot see it in person.
Good luck

David