The actual cost of running a light aircraft is insignificant if the ownership of said aircraft is a joy and fun. Also you can choose something that is not normally available for rent. You can also own something short term and loose very little. You could even turn a small profit. Make it a business or part of a business and get taxation benefits and GST on everything aircraft related back.
I have no real idea what my aircraft have cost to own over the years, I am simply not that interested but the accountant I use has tended to raise an eyebrow on the odd July month of reckoning. Having a supporting partner is also essential. I am only allowed to sell mine if it is to buy another. Mine is a couples activity even though she doesn't fly it herself. It is a holiday and fun machine for the both of us.
Go on, spend the kids inheritance. They will only waste it anyway.