Re-suggesting, using last month

Sale 1:

Sold for Spec. KS Aus SMG (7) + hat (0.5)

http://www.tf2outpost.com/trade/29605685 - B/O of 12

Seller: https://backpack.tf/profiles/76561198253606754#!/compare/1522454400/1522540800

Buyer: https://backpack.tf/profiles/76561198281777040#!/compare/1522454400/1522540800

X = 7.5

Sale 2:

Sold for 7 keys

Seller: https://backpack.tf/profiles/76561198168863803#!/compare/1523577600/1523664000

Buyer: https://backpack.tf/profiles/76561198247572926#!/compare/1523577600/1523664000 (nsfw)

X = 7

Sale 3:

Sold to a quickbuyer for 6 keys

Seller: https://backpack.tf/profiles/76561198277767530#!/compare/1522886400/1522972800

Buyer: https://backpack.tf/profiles/76561198168863803#!/compare/1522886400/1522972800

X = 6

Sale 4:

Sold to a quickbuyer for 5 keys + 2 ref

Seller: https://backpack.tf/profiles/76561198214090164#!/compare/1523232000/1523491200

Buyer: https://backpack.tf/profiles/76561198024867201#!/compare/1523145600/1523232000

X = 5

Sale 5:

Bulk for Fountain of Delight Carlton

Seller: https://backpack.tf/profiles/76561198247572926#!/compare/1524268800/1524355200 (nsfw)

Buyer: https://backpack.tf/profiles/76561197994697258#!/compare/1524268800/1524355200

Sellers:

~6.15 keys:

https://i.imgur.com/z8dCYCq.png

https://backpack.tf/item/4953085785

7 keys:

https://i.imgur.com/cb6Ff38.png

https://backpack.tf/item/4985495185

9 keys:

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

https://backpack.tf/item/5291577790

https://backpack.tf/item/5786015800

11 keys:

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

https://backpack.tf/item/4956353559

https://backpack.tf/item/4965369838

13 keys:

https://i.imgur.com/t06kCGP.png

https://backpack.tf/item/5442896543

15 keys:

https://i.imgur.com/Dcafp60.png

https://backpack.tf/item/4965711996

Sales at:

5

6

7

7.5

Seller at 6 supports 6 being in the range. Excluding 5 though, as it quicksold.

Going with 6-7.5, as requested by K1ng.