Self-employed people can write off payments for extended health. (There are some upper bounds on how much, but generous enough that I think I would have a full write off even with the rather frivolous plans out there.)
I did the number crunching that way, using pre-tax dollars. Of course, it looked better that way, but still a waste of money compared to giving your credit card to the dentist or whoever.
By the way, in British Columbia, if you make a decent income, you are required to pay some $1800 per year to the province for a health care plan called MSP. That is not a business expense you can deduct from your income as a self-employed person, nor a qualifying medical expense for a tax credit.