Assuming that Mark's Cherokees are in decent shape, I think that you would be hard-pressed to beat his price of C$75 per hour (wet).
I assume that the above includes insurance, but if not you will need to factor in an additional amount to ensure that you are really comparing apples to apples. It is standard in Canada for rental prices to include both liability and hull insurance, possibly with a small surcharge if the renter wishes to be exempt from the deductible in the event of a subsequent claim.