Sale 1:

https://backpack.tf/profiles/76561198164528751#!/compare/1553040000/1553212800

https://backpack.tf/profiles/76561198026129220#!/compare/1553040000/1553126400

Untrace

Sale 2:

https://backpack.tf/profiles/76561198179844905#!/compare/1556150400/1556236800

https://backpack.tf/profiles/76561198132504113#!/compare/1556150400/1556496000

Bulk

Sale 3:

https://backpack.tf/profiles/76561198335791307#!/compare/1554595200/1554681600

https://backpack.tf/profiles/76561198811898821#!/compare/1551484800/1554854400

Untrace

Sale 4:

https://backpack.tf/profiles/76561198208582767#!/compare/1555891200/1555977600

https://backpack.tf/profiles/76561198132504113#!/compare/1556064000/1556496000

Bulk

sale 5:

https://backpack.tf/profiles/76561198118157202#!/compare/1556409600/1556668800

https://backpack.tf/profiles/76561198420405812#!/compare/1556668800/1556668800

https://backpack.tf/profiles/76561198118157202#!/compare/1556409600/1556668800

https://backpack.tf/profiles/76561198016663834#!/compare/1556582400/1556668800

https://backpack.tf/profiles/76561198873165470#!/compare/1557014400/1557100800

Untrace

Sale 6:

https://backpack.tf/profiles/76561198873165470#!/compare/1557014400/1557100800

https://backpack.tf/profiles/76561198841279602#!/compare/1557014400/1557100800

Can trace ~2.5 keys

sale 7:

https://backpack.tf/profiles/76561198124809401#!/compare/1555977600/1556064000

https://backpack.tf/profiles/76561198100484031#!/compare/1555977600/1556064000

https://backpack.tf/profiles/76561198088289860#!/compare/1555977600/1556064000

https://backpack.tf/profiles/76561198132504113#!/compare/1556150400/1556496000

Untrace

Sale 8:

https://backpack.tf/item/6666263078

not unusual

Sale 9:

https://backpack.tf/profiles/76561198116571567#!/compare/1553385600/1553472000

https://backpack.tf/profiles/76561198154211785#!/compare/1553299200/1553385600

Bulk

Sale 10:

https://backpack.tf/profiles/76561198154211785#!/compare/1554422400/1554508800

https://backpack.tf/profiles/76561198170008030#!/compare/1554508800/1554768000

Untrace

Sale 11:

https://backpack.tf/profiles/76561198170008030#!/compare/1554508800/1554768000

https://backpack.tf/profiles/76561198018127246#!/compare/1553731200/1556323200

Untrace

sale 12:

https://backpack.tf/profiles/76561198057059610#!/compare/1556409600/1556496000

https://backpack.tf/profiles/76561198063644848#!/compare/1556496000/1556668800

Untrace

Sale 13:

https://backpack.tf/profiles/76561198841279602#!/compare/1552435200/1552521600

https://backpack.tf/profiles/76561198151244565#!/compare/1552435200/1552521600

Sold for ~1.5 keys

Sale 14:

https://backpack.tf/profiles/76561198821221244#!/compare/1554508800/1554595200

https://backpack.tf/profiles/76561198305676157#!/compare/1554422400/1554508800

Sold for ~3.5 keys

sale 15:

https://backpack.tf/profiles/76561198363395191#!/compare/1553212800/1553299200

https://backpack.tf/profiles/76561198340508159#!/compare/1552867200/1553558400

SCM

sale 16:

https://backpack.tf/profiles/76561198302384193#!/compare/1556928000/1557014400

https://backpack.tf/profiles/76561198240537922#!/compare/1556928000/1557014400

https://backpack.tf/profiles/76561198375014774#!/compare/1556928000/1557014400

https://backpack.tf/profiles/76561198240537922#!/compare/1556928000/1557014400

https://backpack.tf/profiles/76561198833814622#!/compare/1557014400/1557100800

Gambling?

sale 17:

https://backpack.tf/profiles/76561197984373540#!/compare/1557360000/1557446400

https://backpack.tf/profiles/76561198030383222#!/compare/1557273600/1557360000

https://backpack.tf/profiles/76561198055747230#!/compare/1557360000/1557446400

https://backpack.tf/profiles/76561198240537922#!/compare/1557360000/1557446400

https://backpack.tf/profiles/76561198220151393#!/compare/1557273600/1557446400

https://backpack.tf/profiles/76561198055747230#!/compare/1557360000/1557446400

https://backpack.tf/profiles/76561198068668018#!/compare/1557446400/1557532800

https://backpack.tf/profiles/76561198080669489#!/compare/1557446400/1557532800

Gambling?

Sale 18 - 25:

https://marketplace.tf/items/30917;5;u3007

$9.98 / $1.8 = 5.54 keys

$8.00 / $1.79 = 4.47 keys

$8.00 / $1.78 = 4.49 keys

$7.99 / $1.79 = 4.46 keys

$5.25 / $1.79 = 2.93 keys

$7.99 / $1.78 = 4.49 keys

$7.50 / $1.79 = 4.19 keys

$7.00 / $1.8 = 3.89 keys

https://bot.tf/stats/item?def=30917&q=5&ef=Skill%20Gotten%20Gains&craft=1&aus=0&ks=0

1 @ 3 keys, 38.88 ref Sold

Bought

1 @ 3 keys, 15.22 ref

1 @ 3 keys, 16.00 ref

1 @ 3 keys, 16.00 ref

1 @ 3 keys, 15.00 ref

Total sales @:

1.5, 2.5, 2.93, 3.32, 3.33, 3.34, 3.34, 3.5, 3.84, 3.89, 4.19, 4.46, 4.47, 4.49, 4.49, 5.54 keys

Buyers up to ~2.75 keys

Sellers down to ~3.79 keys

Gonna take 3 - 4 keys, all high sales mostly MPTF.