just gambles:

https://backpack.tf/item/5371527898

https://backpack.tf/item/7760507550

Sale 1-2:

https://marketplace.tf/items/tf2/30827;5;u6

$12.49 / $1.75 = 7.14 keys

$12.78 / $1.75 = 7.30 keys // https://backpack.tf/item/5371527898

Sale 3:

6 keys + 1 ref

https://backpack.tf/profiles/76561198841279602#!/compare/1582156800/1582243200

https://backpack.tf/profiles/76561198224647756#!/compare/1582329600/1582416000

Sale 4:

untrace

https://backpack.tf/profiles/76561198878866368#!/compare/1582848000/1583020800

https://backpack.tf/profiles/76561198224647756#!/compare/1582502400/1582848000

Sale 5:

untrace

https://backpack.tf/profiles/76561198337734785#!/compare/1584748800/1584835200

https://backpack.tf/profiles/76561198279539667#!/compare/1584748800/1584835200

Sale 6:

untrace

https://backpack.tf/profiles/76561198850274253#!/compare/1585267200/1585353600

https://backpack.tf/profiles/76561198142230904#!/compare/1585353600/1585440000

Sale 7:

untrace

https://backpack.tf/profiles/76561198017911489#!/compare/1585526400/1585612800

https://backpack.tf/profiles/76561198850274253#!/compare/1585526400/1585612800

Sale 8:

bulk

https://backpack.tf/profiles/76561198017911489#!/compare/1585612800/1585699200

https://backpack.tf/profiles/76561198088551406#!/compare/1585612800/1585699200

Sale 9:

bulk

https://backpack.tf/profiles/76561198056974324#!/compare/1585612800/1585699200

https://backpack.tf/profiles/76561198088551406#!/compare/1585612800/1585699200

Sale 10:

bulk

https://backpack.tf/profiles/76561198031743044#!/compare/1585958400/1586044800

https://backpack.tf/profiles/76561198056974324#!/compare/1585958400/1586044800

Sale 11:

untrace

https://backpack.tf/profiles/76561198803791472#!/compare/1579564800/1580428800

https://backpack.tf/profiles/76561198200441733#!/compare/1581724800/1581984000

Sale 12:

6 keys

sold for Planets Bombing Run which was instantly sold for 6 keys, implying he would have taken 6 keys for the warming

https://backpack.tf/profiles/76561197980692654#!/compare/1584144000/1584230400

https://backpack.tf/profiles/76561198084717059#!/compare/1584144000/1584230400

Sale 13:

SCM

https://backpack.tf/profiles/76561198084717059#!/compare/1584230400/1584662400

https://backpack.tf/profiles/76561198315977250#!/compare/1584489600/1584576000

Sale 14:

5 keys + 38 ref - sold to buy order

https://backpack.tf/profiles/76561198315977250#!/compare/1586390400/1586476800

https://backpack.tf/profiles/76561198305494036#!/compare/1586390400/1586476800

==============================================================================

Sales:

5.5, 6, 7, 7.5