The cost is what the depreciation is based on. For cost, you use the *LESSER* of what you paid for it, or the FMV on the date the property was placed in service. While not unheard of, since property values increase over time, it's not very common now-a-days for it to be worth less than what you paid for it. So more than 95% of owners use the price they paid for the property.
Note that if you do not use the price paid for the property, then things get tricky (but not impossible) in the future when you go to report the sale of the property in TurboTax.
