3-star set equipment after Nightmare 9-9

Hello,

I’m trying to finish the 3-star set equipment collection but it seems like all shops no longer sell 3-star set items after Nightmare 9-9?

Is there another way to complete the equipment collection? I’m just missing a few… It’d be disappointing to not be able to get all the equipment collection bonuses :sob:

Thanks in advance,
Tbe3000