Most of the Feather Tokens are highly situational, so in my experience, they are the first things to sell, but if dropped in certain campaigns, or in the possession of a particularly ingenious character, they can be quite effective.
On the same note, ever had a really useful magic item get immediately vendored, for no other reason than it not being optimal, or some other garbage? A player playing a blasty and damage-dealing caster turned down a Staff of Swarming insects in one of my games!