As far as i know, instructors insurance just covers the instructor, not assistants. If i was you, i would not consider assisting without valid insurance. I dislike insurance costs just as much as anyone but IMO diving is not a place to skimp on being covered.O-ring once bubbled...
That if I am only helping an instructor with classes then I do not need my own insurance and that his will cover it since he is the responsible party. Any truth to that? I don't ever plan to DM as a career or earn any money at it...it is strictly for fun.