Sale 1:

https://backpack.tf/profiles/76561198045775820#!/compare/1545609600/1545696000

https://backpack.tf/profiles/76561198068732040#!/compare/1545696000/1545782400

https://backpack.tf/profiles/76561198045775820#!/compare/1546387200/1546473600

Bulk / broker

Sale 2:

https://backpack.tf/profiles/76561198045775820#!/compare/1546473600/1546560000

https://backpack.tf/profiles/76561198341171690#!/compare/1546387200/1546560000

Bulk

Sale 3:

https://backpack.tf/profiles/76561198810755050#!/compare/1547856000/1547942400

https://backpack.tf/profiles/76561198080091915#!/compare/1547856000/1547942400

Bulky

Sale 4:

https://backpack.tf/profiles/76561198080091915#!/compare/1548028800/1548115200

https://backpack.tf/profiles/76561198802184359#!/compare/1548028800/1548115200

Sold with ~5 keys in sweets for C9 Bonnet

Bonnet Mini:

https://backpack.tf/suggestion/5c78fbcc6780725ce0721008

Suggestion for 16.5 keys

Total is 11.5 keys

Sale 5:

https://backpack.tf/profiles/76561198802184359#!/compare/1548028800/1548115200

https://backpack.tf/profiles/76561198045775820#!/compare/1548028800/1548115200

Sold with 1 key for Smoking Stahlhelm

Use there

Sale 6 - 8:

https://marketplace.tf/items/30866;5;u7

$15.00 / $1.8 = 8.33 keys

$20.42 / $1.75 = 11.67 keys

$30.00 / $1.8 = 16.67 keys

Total sales @:

8.33, 11.5, 11.67, 16.67 keys

Sellers down to 12 keys,

Buyers up to ~10 keys

Taking 12 flat.