Lynel / Mighty Lynel Weapons Unobtainable Late Game?

I'm trying to complete my compendium, and I'm missing a few Lynel and all of the Mighty Lynel weapons. But at this point, I'm pretty much end-game and it looks like all the Lynel spawns are now Silver. Is it too late to get these weapons and would I have to pay the guy to have it added?