as of update 2.0 you seem to be unable to buy crafting components, from any vendor. it used to be the only use for junk vendors really, but now they are truly pointless. hopefully this is a bug. if not i'd suggest adding back in at least common components. that way we can craft them into higher tier components as needed. not sure if this was some sort of attempt to halt the crafting, sell, buy components loop for making money.