I get the premise of adjusting prices based on cards used, but increasing the price of the "strongest" cards is completely futile unless they cost like 500+ each. Every team will pack novas, grabbies, dims, deflags, and steals regardless of what the price is. These cards are also going to be the most salvaged and least discarded, thus inflating their "use" and therefore their price.
If you want to limit the use of "strong" cards throughout war, it would be wiser to modify salvage rules rather than market prices. For instance, can only have max 9 copies of an off-element card when building the vault, either keep the max at 9 or maybe limit it to 12 during war.