Sale 1-3:

https://marketplace.tf/items/tf2/339;5;u29

$129.99 / $1.81 = 71.82 keys

$149.99 / $1.78 = 84.26 keys

$140 / $1.67 = 83.83 keys

Sale 4:

69 keys

https://backpack.tf/profiles/76561198305494036#!/compare/1569801600/1569888000

https://backpack.tf/profiles/76561198304001962#!/compare/1569801600/1569888000

Sale 5:

bulk for keys

https://backpack.tf/profiles/76561198304001962#!/compare/1570233600/1570406400

https://backpack.tf/profiles/76561198021055079#!/compare/1570320000/1570406400

Sale 6:

untrace

https://backpack.tf/profiles/76561198021055079#!/compare/1572739200/1572825600

https://backpack.tf/profiles/76561197986438264#!/compare/1572739200/1572825600

Sale 7:

77 keys

36 keys + Sunbeams Blast Defense(41 keys)

https://backpack.tf/profiles/76561197986438264#!/compare/1574553600/1574640000

https://backpack.tf/profiles/76561198031711498#!/compare/1574553600/1574640000

Sale 8:

better used on head warmer

https://backpack.tf/profiles/76561198031711498#!/compare/1574553600/1574640000

https://backpack.tf/profiles/76561198280357510#!/compare/1574553600/1574640000

Sale 9:

77 keys

https://backpack.tf/profiles/76561198280357510#!/compare/1574985600/1575158400

https://backpack.tf/profiles/76561198159410314#!/compare/1574899200/1574985600

Sale 10:

62 keys

https://backpack.tf/profiles/76561198159410314#!/compare/1575158400/1575590400

https://backpack.tf/profiles/76561198080714795#!/compare/1575331200/1575590400

Sale 11:

67 keys

Frostbite Bolted Birdcage(30) + 37 keys

https://backpack.tf/profiles/76561197986438264#!/compare/1575504000/1575590400

https://backpack.tf/profiles/76561198080714795#!/compare/1575331200/1575590400

Sale 12:

88 keys

TF Logo Soldier's Stash(87.5 keys)

https://backpack.tf/profiles/76561198011321852#!/compare/1576108800/1576195200

https://backpack.tf/profiles/76561198084635414#!/compare/1576108800/1576195200

Sale 13:

untrace

https://backpack.tf/profiles/76561198011321852#!/compare/1573689600/1573776000

https://backpack.tf/profiles/76561197990076257#!/compare/1573689600/1573776000

Sale 14:

75 keys

Sunbeams Blast Defense(41 keys) + 34 keys

https://backpack.tf/profiles/76561197990076257#!/compare/1575331200/1575417600

https://backpack.tf/profiles/76561197986438264#!/compare/1575417600/1575504000

Sale 15:

76 pure

https://backpack.tf/profiles/76561197986438264#!/compare/1575936000/1576022400

https://backpack.tf/profiles/76561198863002132#!/compare/1575936000/1576022400

Sale 16:

bulk

https://backpack.tf/profiles/76561198863002132#!/compare/1576195200/1576281600

https://backpack.tf/profiles/76561198117390056#!/compare/1576195200/1576281600

Sale 17:

untrace

https://backpack.tf/profiles/76561198086948995#!/compare/1570233600/1570320000

https://backpack.tf/profiles/76561198116218503#!/compare/1570147200/1570320000

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

Sales:

62,67,69,72,75,76,77,77,84,84,88

buyers at 65 keys: https://imgur.com/a/KYYF94k