Sale 1: ~2 Keys Pure. (Bellow Buyers)

https://backpack.tf/profiles/76561198151054147#!/compare/1561507200/1561593600

https://backpack.tf/profiles/76561198334559541#!/compare/1561507200/1561593600

Sale 2: Untrace.

https://backpack.tf/profiles/76561198334559541#!/compare/1561852800/1561939200

https://backpack.tf/profiles/76561198256876413#!/compare/1562112000/1562371200

Sale 3: Untrace/Low.

https://backpack.tf/profiles/76561198416086593#!/compare/1559779200/1559865600

https://backpack.tf/profiles/76561198305676157#!/compare/1559779200/1559865600

Sale 4: Untrace.

https://backpack.tf/profiles/76561198203403692#!/compare/1560211200/1560297600

https://backpack.tf/profiles/76561198349886701#!/compare/1560124800/1560211200

Sale 5: ~3 Keys Pure.

https://backpack.tf/profiles/76561198873165470#!/compare/1557532800/1557619200

https://backpack.tf/profiles/76561198841279602#!/compare/1557532800/1557619200

Sale 6: ~4 Keys Pure. - https://gyazo.com/30712ca39fb0d1b3adc180a094613c5a - https://gyazo.com/6543d24bd0b09f59951819d4b12d7c0c

Sold For 3 Keys 48 ref.

https://backpack.tf/profiles/76561198841279602#!/compare/1558051200/1558137600

https://backpack.tf/profiles/76561198319739756#!/compare/1558051200/1558137600

Sale 7: Untrace. (SCM)

https://backpack.tf/profiles/76561198319739756#!/compare/1559779200/1559952000

https://backpack.tf/profiles/76561198124222069#!/compare/1559692800/1559952000

Sale 8: ~3.5 Keys Pure.

Sold For 3 Keys 30 ref.

https://backpack.tf/profiles/76561198859916337#!/compare/1556755200/1556841600

https://backpack.tf/profiles/76561198305676157#!/compare/1556755200/1556841600

Sale 9: Untrace/Low.

https://backpack.tf/profiles/76561198305676157#!/compare/1559606400/1559692800

https://backpack.tf/profiles/76561198377170826#!/compare/1559520000/1559692800

Sale 10: Untrace.

https://backpack.tf/profiles/76561198304935264#!/compare/1559260800/1559433600

https://backpack.tf/profiles/76561198033661509#!/compare/1559174400/1559260800

Sale 11: Untrace.

https://backpack.tf/profiles/76561198033661509#!/compare/1559260800/1559347200

https://backpack.tf/profiles/76561198148495750#!/compare/1559260800/1559347200

Marketplace.tf Sales: https://marketplace.tf/items/tf2/30917;5;u3006

Sale 12: ~3.5 Keys.

May 18

$6.60 / $1.82 = 3.63 keys

Sale 13: ~3.5 Keys.

May 27

$6.50 / $1.81 = 3.59 keys

Sale 14: ~3.5 Keys.

Jun 2

$6.62 / $1.81 = 3.66 keys

Sale 15: ~5 Keys. (High)

Jul 7

$9.49 / $1.83 = 5.19 keys

Sale 16: ~3.5 Keys.

Jul 9

$6.21 / $1.84 = 3.38 keys

Sales: 2/3/3.5/3.5/3.5/3.5/3.5/4/5

Going with 3-3.5 keys.

Thanks to scourge for the premium!