This is an exceptionally difficult movie to see. As others have noted, it has not received a DVD release, and the VHS video is difficult to track down and probably prohibitively expensive if found.
I saw it just the once, on TV, about ten years ago, but it made a strong impression on me. Stacy Keach gives a very brilliant performance as that most paradoxical of beings: a likable, humane executioner. He is ably supported by Bud Cort who adds his undertaker character to the gallery of eccentric young men that were his early stock in trade.
I also recall the general atmosphere of levity, a failure to take the central theme of the movie - death - very seriously. This is possibly explained by the fact that in 1970 (or, more probably 1969, when the film is likely to have gone into production) the death penalty itself probably seemed to have become a permanent relic of the past, unlikely to be employed again as the United States joined most of the developed world in rejecting it de facto if not yet de jure. (This abolition was only confirmed in 1972, and was short lived, as it happened.) The movie - although much blacker in its comedy - has a similar feel to "Butch Cassidy and the Sundance Kid" (or its TV doppelgaenger, "Alias Smith and Jones"). In these, the Wild West had been somehow not merely domesticated, but suburbanised, and there was an overlay of late 60s/early 70s Southern Californian sensibilities on the period setting. "The Traveling Executioner" does something similar to the Deep South of the late 1910s.
The return of capital punishment in the U.S. in the late 1970s (and its mounting use in the 80s and 90s) is likely to distort the perceptions of those too young to remember the atmosphere of the time in which the movie was made, when its black humour appeared to be excused by the fact that the actual horrors of execution that it so lightheartedly depicted seemed unlikely to reappear.