Business cards can turn out to be a double edged sword. On the one hand, they can open some doors for hunts on private property. On the other hand, when property is damaged either on their land or nearby, guess what.......you get a call and have to deal with someone else's bad behavior. I made up some business cards some 20 years ago, and quit using them, because it I was getting so many calls to search for lost items such as jewelry, glasses property markers and pipes. It just turned metal detecting into a part time job, which was not the direction I wanted to go. So, I quit using them, got more peace of mind and enjoy the hobby much more. Time is precious, and having to deal with other's losses or complaints or a cheap replacement for a surveyor searching for property pins just wasn't for me.
Good luck with your cards. I am sure others have had success with their business cards. Hopefully they will respond.