Since filigree doesn't work properly with the crafting bank (filigree don't stack) the only alternative way to store filigree without a bag is creating extra accounts to store the filigree. There should be at least one way to earn a decent size augment bag in game and this makes the most sense since everything is in place and all you need to do is add the large augment bag.
Earning 150 planar shards isn't easy.