It's intentionally reserved to one class at the beginning and can't just be outright bought, but feel free to offer one to the players as a reward for rescuing a scientist from the BOFA SYNDICATE's hands. You can also add more items to the stores, that are not listed in the brochure (where I had limited space to work with). Gimmick spheres, different types of medicine, even escape rope if you manage to explain how that works!