Again, "nobody" is buying those cosmetics because demand is far far weaker than supply.
And the reason for the crappy demand is because xp is what the demand is. You can even see from Jagex's Treasure Hunter purchase page, they advertise the reward with an xp star.
To help drive the values of cosmetics up, they must be given some values at least semi-competitive than the xp lamps/stars. Progress boosting garments such as skilling outfits may be one way to do it, and I proposed pet/cosmetic items drop rate boost as a new value-pumping addon to some cosmetics.
12-Jun-2019 23:16:26