Using sales that were less than a month old when I started making this suggestion (29/9)

Sales 1-4:

Sold for $13.78, $12.69, $12.78, & $8.41 on marketplace.tf

https://marketplace.tf/items/30572;5;u3006

https://backpack.tf/item/4219287760 - no b/o

https://backpack.tf/item/4083359281 - no b/o

https://backpack.tf/item/3618312535 - no b/o

http://manic.tf/keyprice/?at=2018-08-31 - $13.78 / $1.88 = 7.33 keys

http://manic.tf/keyprice/?at=2018-09-14 - $12.69 / $1.87 = 6.79 keys

http://manic.tf/keyprice/?at=2018-09-16 - $12.78 / $1.85 = 6.91 keys

http://manic.tf/keyprice/?at=2018-09-20 - $8.41 / $1.84 = 4.57 keys

X = 4.5

X = 7 (2x)

X = 7.5

Sale 5:

Sold for 6 keys

Seller: https://backpack.tf/profiles/76561198174203179#!/compare/1536624000/1536710400

Buyer: https://backpack.tf/profiles/76561198082708308#!/compare/1533513600/1537228800

https://backpack.tf/item/6767239429

X = 6

Sale 6:

Sold with Killstreak Dragon Slayer Scattergun (~1.5) for 7 keys

https://i.imgur.com/bxzD2Od.png - B/O of ~5.5 (after rounding)

Seller: https://backpack.tf/profiles/76561198021055079#!/compare/1538784000/1538870400

Buyer: https://backpack.tf/profiles/76561198394164599#!/compare/1536364800/1539216000

https://backpack.tf/item/4450235139

https://i.imgur.com/pMUmLXz.png

https://i.imgur.com/q1R7uq4.png

https://i.imgur.com/anWQwIp.png

X = 5.5

Other Sales:

https://backpack.tf/item/4450235139 (#1)

https://backpack.tf/item/3617907738 (#2 & #3)

https://backpack.tf/item/3616569568 (#4)

https://backpack.tf/item/5464966315 (#5)

https://backpack.tf/item/4459239300 - mannco stuff

https://backpack.tf/item/3912716359 - not unusual at the time

#1

Bulk for Tesla Coil Screamin’ Eagle

https://backpack.tf/profiles/76561198087127437#!/compare/1536364800/1536537600

https://backpack.tf/profiles/76561198021055079#!/compare/1536451200/1536537600

#2

Untraceable

https://backpack.tf/profiles/76561198433914239#!/compare/1535328000/1535760000

https://backpack.tf/profiles/76561198335791307#!/compare/1535673600/1535760000

https://i.imgur.com/WhmjEQq.png - labelled as 4 keys + 4 ref

#3

Untraceable, labelled as 5 keys + 30 ref on bot.tf

https://backpack.tf/profiles/76561198335791307#!/compare/1538870400/1538956800

https://i.imgur.com/tw9sAOU.png

Buyer is untraceable. However, we clearly 5 keys and 30 ref in the compare link, so I don’t doubt that it did sell for 5 keys and 30 ref. This would round to 6 keys, but we already have a sale at 6, so this is fine to exclude.

#4

Untraceable

https://backpack.tf/profiles/76561198050587675#!/compare/1537401600/1538092800

https://backpack.tf/profiles/76561198139276623#!/compare/1537315200/1537401600

#5

Untraceable, labelled as 5 keys + 24 ref

https://backpack.tf/profiles/76561198305676157#!/compare/1538697600/1538784000

https://i.imgur.com/tw9sAOU.png

Pretty much the exact same situation as #3. correct amount visible, buyer is untraceable, we already have a sale at this price, so fine to exclude.

Sellers:

https://i.imgur.com/eWF3yrq.png

https://backpack.tf/item/3858015186 - 15 keys

https://backpack.tf/item/6262476708 - 28 keys

Sales at:

4.5

5.5

6

7 (2x)

7.5

4.5 is not a common trading point, excluding.

Going with 5.5-7.5.

https://backpack.tf/profiles/76561198394164599#!/compare/1539216000/1539820800

https://backpack.tf/profiles/76561198257264924#!/compare/1539129600/1539648000

untraceable

no other sales.

https://backpack.tf/item/6462553943 - gambled and dumped on scrap

https://backpack.tf/item/4448197507 - scrap

https://backpack.tf/profiles/76561198016119944#!/compare/1540684800/1540857600

https://backpack.tf/profiles/76561198080179568#!/compare/1540598400/1540684800

https://backpack.tf/item/5464966315

probably sold to julia's bot, then transferred to julia's main. untraceable.