Thanks for the feedback, great call! Selling from the Vault used to be auction-only and easy to miss, so I've just pushed an update:
• Tap any Vault piece to sell it to a collector on the spot (80% of its value), move it back to your bins to list in your shop, or put it up at auction (usually pays the most if you can wait).
• Tap "Sell or move several" to pick a bunch of pieces (or all of them) and sell them or send them back to your bins in one go.
Let me know how it feels!