Sale 1:

https://backpack.tf/profiles/76561198057412106#!/compare/1583884800/1583971200

https://backpack.tf/profiles/76561198113194487#!/compare/1583884800/1583971200

Sold for bubbling Marauder + ~3 keys in sweets

Marauder Mini:

https://backpack.tf/suggestion/5ebf1e122c8d3d61d9476bcc

Suggestion for 9.25 keys

Total is 12.25 keys

sale 2:

https://backpack.tf/profiles/76561198113194487#!/compare/1584057600/1584144000

https://backpack.tf/profiles/76561198131081286#!/compare/1584144000/1584230400

Bulky

sale 3:

https://backpack.tf/profiles/76561198131081286#!/compare/1584316800/1584403200

https://backpack.tf/profiles/76561198856548187#!/compare/1584316800/1584403200

sold for Vivid Hottie

sale 4:

https://backpack.tf/profiles/76561198856548187#!/compare/1584316800/1584403200

https://backpack.tf/profiles/76561198196410274#!/compare/1584316800/1584403200

Sold with 2 keys for C9 Merry

Merry Mini:

https://backpack.tf/suggestion/5ebf24d286803e1ab0540214

Suggestion for 14 keys

Total is 12 keys

sale 5:

https://backpack.tf/profiles/76561198196410274#!/compare/1584403200/1584489600

https://backpack.tf/profiles/76561198311400236#!/compare/1584316800/1584403200

Bulky for keys

sale 6:

https://backpack.tf/profiles/76561198311400236#!/compare/1584921600/1585008000

https://backpack.tf/profiles/76561198368339225#!/compare/1585008000/1585094400

Sold for Aces Dogger + negligible sweets

Dogger mini:

https://backpack.tf/suggestion/5ebf3d3b72b09e03eb2e470c

Suggestion for 10 keys

sale 7:

https://marketplace.tf/items/tf2/135;5;u35

$38.52 / $1.82 = 21.16 keys

Total sales @:

10, 12, 12, 21 keys

buyers up to 10 keys,

taking a base thirteen C.