I would also add that if you put items on your list that are not fulfilled by Amazon and you want to return them the process is a pain in the arse.
As the item doesn't appear on your Amazon orders you cannot open a return and have to ask either the Buyer to do so or you have to contact Amazon, explain the situation, ask for the seller's contact info, email them and then you may have to pay return shipping. And in some cases after all that the Buyer will be refunded and not you, as I learned today!
So yeah, only go for Prime items to ensure an easy return process
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