Unfortunatley the average value of a chest has dropped from ~1$ to only 70 DEC or 0.402$ in this new season: https://www.splintercards.com/tool-lootchest.html
As the questing potion is 750 DEC (or ~ 4.2$), when you purchase one, you are loosing on average, 400 DEC (750 - 70*5) or ~2.25$.
Im really tempted by the questing potions but at this point they really arent worth it :(
That being said, good luck to you if you choose to go for it!