First Suggestion, Hopefully it is good :)

Thanks to Vortexan for helping me out

Sale #1 - 2:1 for a Sunbeams Belgian Detective - Unusable considering 2 unpriced for 1 priced

https://backpack.tf/profiles/76561198133703221#!/compare/1534550400/1534723200

https://backpack.tf/profiles/76561198449473770#!/compare/1534550400/1534723200

Sale #2 - ???

https://backpack.tf/profiles/76561198449473770#!/compare/1535068800/1536278400

https://backpack.tf/profiles/76561198853997573#!/compare/1536192000/1537056000

Sale #3 - Sold for 15 Keys 17 ref (Rounding up to 15.5)

https://backpack.tf/profiles/76561198294663533#!/compare/1537401600/1537488000

https://backpack.tf/profiles/76561198800071484#!/compare/1537401600/1537660800

Sale #4 - 1:1 for Blizz. Storm Conjurer's Cowl + 1 Key (16.5 Keys bp.tf value)

https://backpack.tf/profiles/76561198150761253#!/compare/1537574400/1537747200

https://backpack.tf/profiles/76561198294663533#!/compare/1537488000/1537747200

Sale #5 - QS for 11 Keys

https://backpack.tf/profiles/76561198150761253#!/compare/1537747200/1537920000

https://backpack.tf/profiles/76561198044203779#!/compare/1537574400/1537920000

Sale #6 - Sold for 14 Keys

https://prnt.sc/l5deis (Compare is wonky, got screenshot)

Sales at - 14, 15.5, 16.5

Taking range 14-16

Tell me if there is anything wrong, most of this was really wonky.