Resuggesting, thanks Shuffle.

Sales 1 to 6:

24 on june 24 (24/1.84 = 13.04 rounding to 13 keys)

22 on july 19 (22/1.83 = 12.02 rounding to 12 keys)

17.8 on august 18 (17.8/1.84 = 9.67 rounding to 9.5 keys)

17.8 on august 20 (17.8/1.84 = 9.67 rounding to 9.5 keys)

18 on august 26 (18/1.83 = 9.83 rounding to 10 keys)

15.99 on october 19 (15.99/1.81 = 8.83 rounding to 9 keys)

https://marketplace.tf/items/tf2/31024;5;u56

Item history for SALE 1: https://backpack.tf/item/7584074489

Item history for SALE 2: https://backpack.tf/item/7584074489

Item history for SALE 3: https://backpack.tf/item/7426668383

Sale 7: Sold to a bot for unknown

https://backpack.tf/profiles/76561198083975335#!/compare/1564012800/1564185600

https://backpack.tf/profiles/76561198323565601#!/compare/1564185600/1564272000

Sale 8: Sold for 7 keys + 15 refined

https://backpack.tf/profiles/76561198341171690#!/compare/1565654400/1565740800

https://backpack.tf/profiles/76561198118923881#!/compare/1503100800/1565740800

Rounds to 7.5 keys.

Sale 9: Unknown

https://backpack.tf/profiles/76561198099780165#!/compare/1562976000/1563062400

https://backpack.tf/profiles/76561198335791307#!/compare/1562976000/1563062400

Sale 10: Sold for 9 keys + 19 refined

https://backpack.tf/profiles/76561198309328337#!/compare/1563840000/1563926400

https://backpack.tf/profiles/76561198335791307#!/compare/1563840000/1563926400

(Histories match up for the first comparison link)

9.37 rounding to 9.5 keys

Sale 11: Unknown

https://backpack.tf/profiles/76561198084088691#!/compare/1563408000/1563580800

https://backpack.tf/profiles/76561198237292756#!/compare/1561939200/1564099200

Sale 12: Sold for 7 keys + 6 refined

https://backpack.tf/profiles/76561198086192598#!/compare/1567468800/1567641600

https://backpack.tf/profiles/76561198323565601#!/compare/1567555200/1567641600

Sold to a buy order, low.

7.12 rounding to 7 keys

Sale 13: Sold for 7 keys + 6 refined

https://backpack.tf/profiles/76561198314017078#!/compare/1567036800/1567814400

https://backpack.tf/profiles/76561198080179568#!/compare/1567728000/1567814400

Sold to a buy order, low.

7.12 rounding to 7 keys

Sale 14: Sold for 7 keys + 20 refined

https://backpack.tf/profiles/76561198358482558#!/compare/1565913600/1566000000

https://backpack.tf/profiles/76561198237292756#!/compare/1565913600/1566000000

https://imgur.com/a/3Kh5rVX

7.39 rounding to 7.5 keys

Classifieds:

https://gyazo.com/cbe64759d4d57f9003f9667df823ef49

Conclusion:

Sales at 7, 7, 7.5, 7.5, and 9.5. Marketplace sales at 9, 9.5, 9.5, 10, 12, and 13.

7 is low due to the sales being to buy orders, as well as a buyer at 7. 12 and 13 are high due to sellers at 10. Shuffle suggested to take a range of 7.5 - 9.5, but I don't see a reason to exclude 10.

Taking 7.5-10 keys.