Something is property because I created it and will dispose of it for my own personal reasons. I think - I work to bring that thought into reality. The product of that thought is an object I plan to use to advance my life. I have property in the object since my ability to thrive is dependent on acting on my thoughts by disposing of that object. It can be unique or common, it doesn't matter. It's availability is not an issue ethically, only economic. Something is property because it is mine. It can be the only one in the world or I can craft a pebble like a billion others. It is mine. Of value to me. Scarcity only becomes relevant if I choose to trade it. A unique item may be worth a lot. A pebble will likely only hold value to me.
I give the object value, not any random attribute it has in nature.
If anything the scarcity argument is only reinforcing the fact property is a moral concept devoid of any measurement, which demonstrates the full evil of the situation. Wealth has to be produced before it can be looted. Man's mind is the source of all values and the ultimate vale that creates other values. How despotic is it then to preempt the welfare state looting and go straight for the source and take a man's thoughts?
Just to trow my two cents into the subject of the Tea Party; I went from being a Republican, to a Tea Party Member (Like to think I still am one) to Libertarian, then to a student of Objectivism. I agree that the forming of Tea Party was an emotional response, but one that can lead to the rational conclusions of Objectivism.
Can't be too bad, can it?