People ask for it because they like numbers and the meta kiddies tell them they need it.
I absolutely support selling it to the idiots who don’t know any better, but it isn’t at all worth the cost.
Nope. But Frost is coming out of the vault next month and you can farm it then instead of buying it. (Especially considering that Frost parts can be rather expensive)
I don’t have them, no. But Trin is still dirt-cheap, so it should not be tough to find really cheap.