Prices in echoes don't respond like prices on a market ought to. There are spikes here and there but increases in money supply, through ratting changes don't appear to have any impact on commodity prices. PI and mineral prices have only ever gone down.
For a few items you can see market effects like faction wrecks you can see the impact from the drop nerf and from increasing demand for them as people started building Battleship BPs. But for core minerals there's been just steady or slowly declining prices.
Anecdotally, when I make sell orders for PI there are occasionally a few buys at first but then if the sell price moves far off my original price the order sits until it's about to
