Vestiaire Collective is an online store where anyone can sell their pre-loved luxury items, or buy them from people who are. Conde Nast - the owner of Vogue - invested in VC recently, after seeing the potential. I already spoke about it here, and now I can report back and share my experience with them. I sold my first item via VC in November, and I have been a regular seller on there ever since. I haven't yet had a chance to buy, so I will speak from my selling experiences.
What I love the most about VC is that it's free to publish items you're trying to sell. Vestiaire Collective will not charge you anything until you actually sell the item. What percentage of the full price paid by the buyer they take depends on the price of your item. After an item is bought, you send it to VC where their professionals carefully inspect and check each item, making sure it is authentic and fits the description and after confirming it, they send it to the buyer. After the item is checked you receive your money immediately to your VC account, and you can then choose to transfer it to you bank account or use it to buy an item from VC.

I have sold 8 items so far and only have the best to say about Vestiaire Collective and highly recommend it, because of their good service and the selection of vintage and preowned designer items which is quite incredible. Some of the items are barely even worn or still have tags on them even, but not the retail price tag. I know I love a good bargain.