There is no official date when the exposition store will be available. If you want to see what were the potential Exposition packages and items for EP store check CoE Kickstarter: https://www.kickstarter.com/projects/soulboundstudios/chronicles-of-elyria-epic-story-mmorpg-with-aging/description
There you can see some concept for EP items, they took EP Store because it required reconfiguration as well they said it will be released closed towards EP release so they have time to polish everything and adjust prices accordingly