Sale 2 on Item 1 is more straightforward than you think. It sold for that C.A.P.P.E.R, which seems to have been around 7-9 Keys at the time.

12 already felt low with an active buyer at 12 Keys, but knowing it ended up reselling for less makes it even more of an outlier here. Conversely, these sales happening also make 20 Keys feel high in contrast.

15-18 should be fine here.