I'm not sure why a business would do this. It seems to be a money losing venture.
Supposedly, Groupon takes 50% right off the top. Therefore, $249 becomes a net of $124.50, less HST, so $111 to the shop.
PADI charges the shop for the Crewpack and PIC, so subtract that expense (no idea how much), but lets say $80, which leaves $31.
Initially that seems to be alright, but you haven't paid your instructors or DMs yet.
Once you've paid to teach the students, I can't see how you'd have anything left over other than red ink.
Sure, there will be some people who don't take the class, but if I couldn't, I'd find a reason to get my money back or transfer it to someone else, etc. All you have to do is answer YES on any of the medical questions and you get a refund.
And there will certainly be those students that buy gear, take another class, etc., but the economics of the deal still don't make sense to me.
I'm quite intrigued by this and of course am completely speculating/hypothesizing. It sounds like a great deal for the customer and I hope the shop has an ace up their sleeve to make it profitable for them, otherwise, we may be attending a going-out-of-business sale and getting even better deals.