I definitely prefer buying new, but wouldn't be against buying pre-loved if there was a discontinued design or colour I wanted, especially if the condition and price are very appealing. As for authentication and date codes, any authenticator worth their salt would not need to rely on a date code to determine if the bag is genuine or counterfeit as there are several other ways to tell. Places such as Yoogi's Closet and
Fashionphile are highly reputable, but with eBay buyer beware...it's highly recommended that one would use a third-party to authenticate for both proof and peace of mind.