In every transaction made between commoners there is an object that has a cost and value to the object's holder and its seeker. The object has more cost than value to its holder so it is put up for sale. If the price of the object is right for the market, then for its seeker it has a greater value than cost. In a satisfactory trade the objects holder recieves the value of the seekers cost which is greater than or equal to the holders cost. To the seeker the cost is less than or equal the value of the object. Both satisfied, the trade is complete.
There is, however, a HUGE FUCKING LOOPHOLE that few, very few, observe. This is an entity that can give value at no cost to itself. This group is called the Federal Reserve. The Reserve can pay debts and purchase objects without losing any value in their holdings. This is because they create USD (united states dollars). They just create it. USD also happens to be what 98% of the worlds currency is backed by. Every time the Reserve creates money it is diluting the value of 98% of the worlds money. Think about that.