I saw one like that too....just yesterday.
Some guy was apparently trading his leprechaun amulet for Heartseekers knives. So another guy found out about that. He sold 4 crates to me for 48k so he can buy the knives. Then when he went to the scammer, the scammer probably told him that he didn't need it or just left or something. So he spent about 65k for the knives, and the knives were probably listed by the scammer's alt.