Resuggestion, thanks to K1ng for the info!

Sale 1:

https://backpack.tf/profiles/76561198176088318#!/compare/1550275200/1551744000

https://backpack.tf/profiles/76561198080179568#!/compare/1552003200/1552089600

SCM

Sale 2:

https://backpack.tf/profiles/76561198088277076#!/compare/1549324800/1549411200

https://backpack.tf/profiles/76561198326809927#!/compare/1549411200/1549497600

Untrace

Sale 3:

https://backpack.tf/profiles/76561198063418484#!/compare/1547337600/1548115200

https://backpack.tf/profiles/76561198075146778#!/compare/1547164800/1547510400

https://backpack.tf/profiles/76561198869782699#!/compare/1547424000/1547510400

https://backpack.tf/profiles/76561198841707825#!/compare/1547424000/1547510400

https://backpack.tf/profiles/76561198232157836#!/compare/1547424000/1547510400

https://backpack.tf/profiles/76561198840858484#!/compare/1547596800/1547683200

Gambling

Sale 4:

https://backpack.tf/profiles/76561198840858484#!/compare/1547596800/1547683200

https://backpack.tf/profiles/76561198808070411#!/compare/1547683200/1547769600

https://backpack.tf/profiles/76561198236669300#!/compare/1547683200/1547769600

Untrace

Sale 5:

https://backpack.tf/profiles/76561198236669300#!/compare/1547769600/1547856000

https://backpack.tf/profiles/76561198032448583#!/compare/1547769600/1547856000

Untrace

Sale 6:

https://backpack.tf/profiles/76561198032448583#!/compare/1547683200/1547769600

https://backpack.tf/profiles/76561198327837250#!/compare/1547769600/1547856000

Untrace

Sale 7:

https://backpack.tf/profiles/76561198327837250#!/compare/1547856000/1547942400

https://backpack.tf/profiles/76561198390122058#!/compare/1547769600/1547942400

Sold for Ominous Burst + 2 keys

Use there

Sale 8:

https://backpack.tf/profiles/76561198390122058#!/compare/1548633600/1548892800

https://backpack.tf/profiles/76561198080436316#!/compare/1548806400/1548892800

Sold for 15 keys (used to buy glove)

Sale 9:

https://backpack.tf/profiles/76561198080436316#!/compare/1548806400/1548892800

https://backpack.tf/profiles/76561198119149660#!/compare/1548806400/1548892800

Bulk

Sale 10:

https://backpack.tf/profiles/76561198119149660#!/compare/1550448000/1550534400

https://backpack.tf/profiles/76561198157434250#!/compare/1550534400/1550707200

https://backpack.tf/profiles/76561198048851745#!/compare/1550534400/1550620800

Untrace

Sale 11:

https://marketplace.tf/items/604;5;u58

$27.99 / $1.75 = 15.99 keys

Total sales @:

15, 15.99 keys

2 sellers for 14 keys,

K1ng's Part:

In sale 8, the two keys that appear here (and were part of the 15 keys) don't match with the Tavish, so it had to sell for 13 keys:

https://backpack.tf/profiles/76561198390122058#!/compare/1548633600/1548892800

So resuggest at 13-16 keys