Resuggestion, thanks to polar for the info!

Sale 1:

https://backpack.tf/profiles/76561198341612787#!/compare/1538697600/1539129600

https://backpack.tf/profiles/76561198227756380#!/compare/1538611200/1538697600

Sold for 10 keys

Sale 2:

https://backpack.tf/profiles/76561198227756380#!/compare/1543449600/1546128000

Bulk

Sale 3:

https://marketplace.tf/items/701;5;u32

Low, about 9.27 keys

polar's Part:

Sale at 10 went to a quickbuyer

https://backpack.tf/profiles/76561198068130198#!/compare/1539388800/1548633600

Use the SCM sale. It went for 24.58

Sold for 32.66 CAD

Keys at 3.00 CAD

Total is ~10.8 keys

Mindacos' Part:

More sales:

Bulk for Hearts Tank Top

https://backpack.tf/profiles/76561198229149424#!/compare/1548806400/1548979200

Better used for that.

Sold for 15 Keys and minor sweets

https://backpack.tf/profiles/76561198344316001#!/compare/1550534400/1550620800

I guess the fact that it took us this long to get a sale above 11 means that it's still justified to include it in the range. The tank sale above also seems to support 11 as well.

Nevertheless, 11-15 will be fine with this new sale in mind.