Dang, I wish I could have gotten my OW cert in a $99 class. It amounted to only a little more than simply the cost of entry to learning by doing. For me the basics were enough for round one. That seems to hold for the novice divers I come across as well - the majority appear to enjoy the sport, even those with crude skills. Would they all be diving if the OW pitch had been a claim they'd be a lot better, but at twice the price? Would there be even more of them?
If you need or want $500 worth of coaching, by all means get it, and no doubt there are instructors who can command that kind of fee. Lucky for their students... Surely there's also a large contingent of prospects who'd just like to get on with practicing on their own, and appreciate not overpaying for the instruction they're likely to get. It's not rocket science (for everyone).