Winchester rifles, starting with the '66 44/40 were commonly called "Yellow Boy" by the Indians because of the brass furniture.  This was the first Winchester, the second being the Winchester "73 known as the "gun that won the West".  There were many variations of Winchesters which makes them an interesting antique for collectors.  The '66 Winchester was available to General Custer, but he chose not to use them as they were not government issue and he stayed with the single shot (government issue) weapon.  The Indians, on the other hand, did use the multiple shot, lever action Winchesters resulting in a massacre that well could have played out differently had both sides been using the Winchesters.
These weapons are increasing in value because of the recent closing of the Winchester factory in Connecticut creating scarcity. Also, condition is always an important governing factor. Winchesters are at a premium.