I know of nothing for which the price has gone down. Even after all the breakthroughs in fracking technology and a drop in crude prices, gasoline still costs more than it did when that Lazy, Ignorant, Stupid, Mouthy and Arrogant Liar got into Office.
Of what do you know for which the price has declined?
Tech products?
Probably the price of houses in some remote town, where the industry fled, has fallen somewhat. So that must be factored in, you know.