Everything fluctuates in price, from hay to gold. Price is determined by the market, not by the thing itself. Nothing has an intrinsic value in and of itself, so the very concept of self-worth is wrong. A painting may have been bought at a great price during times of plenty. In a famine no one would give even a crust of bread for it.
Value is set by circumstances independent and outside of the object.
It is not an intrinsic quality of the thing itself. There is no way to attach the price paid to the object purchased. Thus, the entire idea of self -worth is false.