Sale 1:

https://backpack.tf/profiles/76561198863452014#!/compare/1549324800/1549497600

7 keys, low

Sale 2:

https://backpack.tf/profiles/76561198334946156#!/compare/1551139200/1551312000

Non Craftable Summer Hat + ~ 15.66 refs in sweets = 8.94 keys

(summer hat mini https://backpack.tf/suggestion/5cb4bed6d3817205c4199be8)

Sale 3:

https://backpack.tf/profiles/76561198133691426#!/compare/1551225600/1551312000

Smoking Head Hot Air + 1 key, use there.

Sale 4:

https://backpack.tf/profiles/76561198133691426#!/compare/1551312000/1551484800

https://backpack.tf/profiles/76561198309261884#!/compare/1551398400/1551484800

idk

Sale 5:

https://backpack.tf/profiles/76561198133691426#!/compare/1551398400/1551657600

idk, Terror-Watt is another trade

Sale 6:

https://backpack.tf/profiles/76561198854043166#!/compare/1551571200/1551657600

https://backpack.tf/profiles/76561198133691426#!/compare/1551571200/1551744000

idk

Sale 7:

https://backpack.tf/profiles/76561198143904636#!/compare/1551657600/1551744000

Scotch + festive shotgun, I WILL use there!

Sale 8:

https://backpack.tf/profiles/76561198143904636#!/compare/1551830400/1552003200

sold with sweets for bubbling cannon, use there

Sale 9:

https://backpack.tf/profiles/76561198362008411#!/compare/1551916800/1552176000

idk, but zol is qs/qbing, so does not matter

Sale 10:

https://backpack.tf/profiles/76561198342161127#!/compare/1550361600/1550534400

https://backpack.tf/profiles/76561198348738792#!/compare/1550275200/1550534400

idk

Sale 11:

https://backpack.tf/profiles/76561198405414405#!/compare/1548720000/1549152000

8 keys + a few refs, under buyorders.

Sale 12:

https://backpack.tf/profiles/76561198207895451#!/compare/1548892800/1549843200

https://backpack.tf/profiles/76561198379444897#!/compare/1548720000/1549497600

idk

Sale 13:

https://backpack.tf/profiles/76561198028171245#!/compare/1547683200/1547856000

9 keys

Sale 14:

https://backpack.tf/profiles/76561198309825646#!/compare/1547769600/1547856000

dumped on scrap, for idk

Sale 15:

https://backpack.tf/profiles/76561198061584202#!/compare/1547510400/1548288000

?

Sale 16:

https://backpack.tf/profiles/76561198414250681#!/compare/1548633600/1548806400

?

Sale 17:

https://backpack.tf/profiles/76561198116002030#!/compare/1546387200/1554681600

?

Sale 18:

https://marketplace.tf/items/249;5;u33

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

15.99$ on Feb 18th, keys were 1.79$ ea

8.932 keys

Sale 19:

https://marketplace.tf/items/249;5;u33

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

19$ on Feb 22nd, keys were 1.81$ ea

10.49 keys

Sales: ~9 keys, 9 keys, ~9 keys, 10.5 keys, 10.5 is outlier so flat 9 keys.