Resuggestion, thanks to Cashew for the info!

Sale 1:

https://backpack.tf/profiles/76561198061755956#!/compare/1565395200/1580947200

https://backpack.tf/profiles/76561198808482503#!/compare/1580342400/1580947200

https://backpack.tf/profiles/76561198382290208#!/compare/1580860800/1580947200

https://backpack.tf/profiles/76561198080179568#!/compare/1580860800/1580947200

Bulk, QS, QS

sale 2:

https://backpack.tf/profiles/76561198260736403#!/compare/1584230400/1584316800

https://backpack.tf/profiles/76561198177872379#!/compare/1584230400/1584316800

untrace

sale 3:

https://backpack.tf/profiles/76561198177872379#!/compare/1584403200/1584489600

https://backpack.tf/profiles/76561198166855771#!/compare/1584316800/1584489600

Sold for 7 keys

sale 4:

https://backpack.tf/profiles/76561198166855771#!/compare/1584921600/1585008000

https://backpack.tf/profiles/76561198838788284#!/compare/1584921600/1585008000

Bulk

sale 5:

https://backpack.tf/profiles/76561198838788284#!/compare/1585094400/1585180800

https://backpack.tf/profiles/76561198051597690#!/compare/1585180800/1585267200

Sold for KaW Whoopee(10.5) + ~0.5 keys in sweets

Total is ~11 keys

Sale 6:

https://marketplace.tf/items/tf2/146;5;u12

$17.5 / $1.79 = 9.78 keys

Total sales @:

7, 10, 11 keys

unsold for 3 months at 10 keys,

buyers up to 7 keys,

Cashew's Part:

https://backpack.tf/item/399894786 seller at 9 for 12 days. With keys now at ~1.9, the current marketplace seller at $17.5 is at 9.2 keys.

Feel free to try 9-10, but it may get left up for a bit.

Taking 9 - 10 for now.