In the 8 years I've been in Tucson I've seen one of them.. Maybe common but there are only a couple snakes I've seen less of... The one I did see, it was late at night and I almost hit it.. It was on my list of snakes I wanted to keep so I kept it for about 6 months and can't remember if I gave it to a friend or what.. It ate insects without any issue as was a very fun and rewarding snake to work with.. I got more joy from it then I did some of the $1,000 snakes in my collection.. Good luck finding one, I'm sure there are areas that people see them every day..
Another hard to find and odd snake is the banded sand snake, I would look into those as well as I kept both and enjoyed both equal although I never saw the sand snakes so maybe they never did eat.. You know what, stay away from the sand snakes