Got a little bit of time.

Taking last 2 months.

Sale 1: Bulk for their bp

https://backpack.tf/profiles/76561198309612194#!/compare/1568073600/1568160000

https://backpack.tf/profiles/76561198168863803#!/compare/1568073600/1568160000

Sale 2: Unknown

https://backpack.tf/profiles/76561198345192210#!/compare/1572220800/1572393600

https://backpack.tf/profiles/76561198004290305#!/compare/1572048000/1572134400

Probably keys, but the sellers bp histories are kinda messed up.

Sale 3: Sold for 8 keys?

https://backpack.tf/profiles/76561198124728984#!/compare/1568937600/1569024000

https://backpack.tf/profiles/76561198345192210#!/compare/1572134400/1572393600

Histories don't match due to the buyers bp, isn't confirmed, so not using it.

It is supportive though.

Sale 4: Sold for 6 keys + 30 refined

https://backpack.tf/profiles/76561198266894571#!/compare/1568246400/1568332800

https://backpack.tf/profiles/76561198124728984#!/compare/1568246400/1568332800

6.59 rounds to 6.5 keys

This was a dumped sale after being purchased for 7. Excluding.

Sale 5: Sold for 7 keys

https://backpack.tf/profiles/76561198048851745#!/compare/1568073600/1568246400

https://backpack.tf/profiles/76561198266894571#!/compare/1550102400/1568246400

Excluding due to buyer selling for less instantly (see sale 4).

Sale 6 & 7:

Sold for 13.79 on september 11

Sold for 14.8 on september 19

https://marketplace.tf/items/tf2/626;5;u31

https://backpack.tf/item/1078158408 - sale 6

13.79/1.8 = 7.66 rounding to 7.5 keys

14.8/1.83 = 8.08 rounding to 8 keys

Classifieds:

https://gyazo.com/8a57e77f3334f6e2385b888c96020779

Conclusion:

Marketplace sales at 7.5 and 8. Supportive sale at 8.

Taking 7.5-8 keys.