I don't mean to rain on your parade, but the Minox B is the most prevalent of the Minoxes and therefore perhaps not the most valuable to collectors (unless it's gold
.) That being said, if it is in working condition, by all means use it!
If you are searching for film, Blue Moon Camera & Machine
in the United States sells, processes and prints Minox film.
Or, purchase/make a film slitter and enter the world of subminiature photography. It isn't easy, but the rewards are worth it (speaking as a full-time Minox user.)