There really was a "Ned Buntline" or rather there was a writer named Edward Zane Carroll Judson, Sr., who used Buntline as a pen name. Google "Ned Buntline" for more information; the Wikipedia article appears to be accurate.
Colt made a number of long barrel revolvers (12") in that period (IIRC the cost was $.50 for each extra inch) so the story of Judson presenting such guns to Wild West characters has at least some basis in fact.
An original "Buntline Special", if found and authenticated, would probably bring in the high six figures.
Jim