If this is a genuine New in the Box First generation SAA in the original factory box, there will be lights flashing, sirens wailing, flares firing, and air horns blaring in collectors homes all over America.
A Teddy Roosevelt era model would probably be a smokeless model.
A NIB standard revolver would be worth AT LEAST $16,000 and you'd add at least 20% for the box, and another 20% for it being a pre-1900 gun.
This is a BARE minimum of value, and very likely at auction with a big auction house, the value would be considerably higher.
This is one case where the $100.00 Colt Historical Letter would be money well spent.
This letter is what Colt knows about the gun from a search of the company records.
It would include the exact model, barrel length, caliber, grips, finish, and any other options that were added at the factory.
Also included will be the date shipped, and who it was shipped to.
For full details on the letter, see the Colt web site:
http://www.coltsmfg.com