Money laundering is definitely a possibility since you can buy amazon gift cards directly from PayPal. I also think some items (not necessarily these gift cards) are being used as placeholder items for a product or service (drugs, etc). For instance I saw a very commonly available $2 bottle of salad dressing go for $20 the other day. I was intrigued and saw that a lot of items from the seller had sold for mulitples of their market value.