Basically I just bought things that I knew I would need or sort of wanted anyway when I was approaching the stupidly low 2,000 myth cap and hadn't acquired all of my atma yet. Quenching oils, mists, etc. are good if you intend at all to level another job. Crafting items from myth are selling for less gil everyday unfortunately (for you), but there are options. Nothing as nice as going over the very low 2K cap, but there are things you can do with the surplus.