Can I buy a property without a loan, or any lenders?

[Michael Grigorashenko]

I was wondering is someone using this strategy or I thought of a new strategy.  Is it legal? Say I found a property that I want to buy.  The owner agrees to sell me the property under this condition. We sign a contract that states if I don't pay off this property within say 15 years, the property is his and I loose the money I invested into it, to pay it off. But say I pay it off the amount we agreed on the property it's mine.   let me know what you guys think!!!