I am thinking about buying a used SCBA for use in some very dusty environments at home. Has anyone here ever done that? I was thinking about a decently priced pack, tested, mask, and couple of bottles that are well within date. I will check with a local SCUBA shop for filling, (I don't know what departmental policy is regarding this, as we have several filling stations, but I do not want to take a chance). I have used several brands in my career, so I am not picky. Thoughts? Suppliers?