Caffeine

https://backpack.tf/item/4502684719

Sale 1) Sold to a quickbuyer for 6 Keys + 18 Refined

https://backpack.tf/profiles/76561198070593964#!/compare/1544572800/1544659200

Sale 2) Sold for $19.79 when Keys were ~$1.75 each

https://marketplace.tf/items/1113;5;u3006

https://marketplace.tf/items/5021;6/Mann%20Co.%20Supply%20Crate%20Key

19.79 / 1.75 = 11.31, which rounds to 11 Keys

https://backpack.tf/item/3488278218

Sale 3) Sold for $17.74 when Keys were ~$1.79 each

https://marketplace.tf/items/1113;5;u3006

https://marketplace.tf/items/5021;6/Mann%20Co.%20Supply%20Crate%20Key

17.74 / 1.79 = 9.91, which rounds to 10 Keys

https://backpack.tf/item/3162244626

Sale 4) Sold for $22.69 when Keys were ~$1.81 each

https://marketplace.tf/items/1113;5;u3006

https://marketplace.tf/items/5021;6/Mann%20Co.%20Supply%20Crate%20Key

22.69 / 1.81 = 12.53, which rounds to 13 Keys

https://backpack.tf/item/3384188949

Sale 5) Bulk sale

https://backpack.tf/profiles/76561198119149660#!/compare/1549324800/1549411200

https://backpack.tf/item/3427336021

Sale 6) Sold for a Nuts and Bolts Honcho's Headgear + 3 Keys

https://backpack.tf/profiles/76561197961279983#!/compare/1549065600/1549238400

https://imgur.com/a/JTD7wli - The Honcho has no Mini, but it has a young Seller at 10 Keys and Buyers at 9 Keys. This sale is somewhere around 12 - 13 Keys.

https://backpack.tf/item/1092861052 - The Honcho Seller at 10 Keys

https://backpack.tf/u/76561198012613726 - Buyer #1 at 9 Keys

https://backpack.tf/u/76561198337734785 - Buyer #2 at 9 Keys

https://backpack.tf/item/7112014111

Sale 7) Bulk sale

https://backpack.tf/profiles/76561198092371264#!/compare/1546041600/1546128000

Sale 8) Sold for 7 Keys + 9 Refined

https://backpack.tf/profiles/76561198075991823#!/compare/1546387200/1546473600

Sale 9) Sold for an Australium Axtinguisher (~5.4 Keys) + Fountain of Delight Trackman's Touchdown

https://backpack.tf/profiles/76561198353861086#!/compare/1546560000/1546646400

Fits in the range.

Trackman Mini

https://backpack.tf/profiles/76561198839523336#!/compare/1549065600/1549152000 - Sold + ~2.8 Keys for an Aces High Pugilist's Protector

https://backpack.tf/profiles/76561198088092045#!/compare/1546560000/1546646400 - Quicksold for 4 Keys + 20 Refined

Sale 10) Sold for an Aces High Swagman's Swatter

https://backpack.tf/profiles/76561198361891514#!/compare/1547078400/1547164800

Fits in the range and could be used to update the Swatter since it was last priced 2 years ago.

Sale 11) ?

https://backpack.tf/profiles/76561198072929068#!/compare/1547078400/1547164800

Sale 12) ?

https://backpack.tf/profiles/76561198291789666#!/compare/1547164800/1547251200

Sale 13) Sold for ~11 Keys of Items

https://backpack.tf/profiles/76561198156102966#!/compare/1546300800/1547164800

https://marketplace.tf/items/1113;5;u3006 - Sold for $19.99 when Keys were ~$1.75 each and $22.99 when Keys were ~$1.80 each

https://marketplace.tf/items/5021;6/Mann%20Co.%20Supply%20Crate%20Key

19.99 / 1.75 = 11.4, which rounds to 11 Keys

22.99 / 1.80 = 12.8, which rounds to 13 Keys