I own a C 150, and a Teal flying boat (so no rental costs), capital investment, which I should recover one day. I own the runway and hangar (so no storage costs), more capital investment to recover one day.
I maintain the property all myself, so some labour cost there, let's say 2 hours a week for the "flying" portion of the property.
I do my own maintenance on both, so let's say 25 hours per year on each.
So, 154 hours a year of my time x $30/hr = $4620 of my time.
Insurance for both together = $2200
I fly each 50+ hours a year
Consumables and reserves $15 per hour for each = $1500
Gas and oil $50/hour for the 150, $100/hour for the Teal = $2500 + $5000
So, the 150 = $148.20 per hour, and the Teal $198.20 per hour.
So, it would be cheaper to rent, but I like having each at my sole disposal, and at home.
My friend in Norway priced out his 182 amphibian, and came up with very close to 500 Euros per hour, just for reference.