Resuggestion, thanks to Vincentius for the info!

Sale 1:

https://marketplace.tf/items/tf2/47;5;u35

$18.89 / $1.89 = 9.99 keys

Vincentius' Info:

another history https://backpack.tf/item/819161045 (with more sales)

and my trades since they are untrace without ss

https://gyazo.com/219c8f14e1c8f801a87ac36ce83cb183

my purchase

https://gyazo.com/a3837094bf3fcac2dde65fbb317cf391

Sale 2:

https://backpack.tf/profiles/76561198337734785#!/compare/1584662400/1584748800\

https://backpack.tf/profiles/76561198295475349#!/compare/1584057600/1585353600

Sold for ~9.5 keys

Sale 3:

https://backpack.tf/profiles/76561198295475349#!/compare/1585353600/1586563200

https://backpack.tf/profiles/76561198080179568#!/compare/1585267200/1585353600

QS

sale 4:

https://backpack.tf/profiles/76561198040186479#!/compare/1586217600/1586131200

https://backpack.tf/profiles/76561198144414148#!/compare/1535846400/1586390400

https://gyazo.com/219c8f14e1c8f801a87ac36ce83cb183

Sold for HG Crack(10.5) + 2 keys

Total is 12.5 keys

sale 5:

https://backpack.tf/profiles/76561198278067898#!/compare/1587513600/1587600000

https://backpack.tf/profiles/76561198206831569#!/compare/1587513600/1587600000

Sold with 3 keys for OF Fuku(11.5)

Total is 8.5 keys

Sale 6:

https://backpack.tf/profiles/76561198206831569#!/compare/1587600000/1587686400

https://backpack.tf/profiles/76561198089253101#!/compare/1587600000/1587686400

Untrace

bit unsure about using the buy, mannco trade and all that.

Total sales @:

8.5, 9.5, 10, 13 keys

gonna call 13 high,

8.5 close to buyers,

taking 9.5 - 10 keys