The Model 58's are pretty uncommon. Not rare, but certainly uncommon. Total production was 20,287 guns between 1964 and 1977. They were built originally for police use and the ammunition makers at first only had the hot loads available. Later came out with a lower powered lead load for police, but it was already too late. Your everyday policeman could not deal with the recoil, but the caliber did exactly what it was intended to accomplish as it was better than a 357 mag. Some police used them. I believe San Francisco issued them. The administrators believed they were simply more than the average policeman could master from a shooting point of view. So, interest died off. Today, the 41 mag is probably more popular than it ever has been, but no where near the popularity of the 44 mag.
Most sportsman bought the adjustable sighted version, Model 57. If you can get the Model 58 at a fair price, buy it. You will not regret it. This is one of the guns made by Smith that have really climbed in value and will continue to do so.