This is a resuggestion.

Please see seasons 1, 2, and 3 for omitted information and proper explanations.

https://backpack.tf/suggestion/5c8d26b9678072154d3c3e18

https://backpack.tf/suggestion/5cb2d2c4d38172250552d9b0

https://backpack.tf/suggestion/5ce03708678072171417c03f

Usable sales:

Sale 1:

https://backpack.tf/profiles/76561198169109536#!/compare/1554940800/1555027200

https://backpack.tf/profiles/76561198073715461#!/compare/1554940800/1555027200

Sold for Strange Pro KS Festive Medi Gun, Strange Pro KS Aus. Blutsauger, Strange Invis Watch, Midnight Whirldwind Skullcracker, Burly Beast, Giger Counter, 100 keys

SF Pro Medi Gun:

https://marketplace.tf/items/663;11;kt-3

Sales around 30 keys and some weird highs and low

https://gyazo.com/2e30b7c102447aba80a1ec8d8eee8f1b

Bot.tf has a sale for 25, going with 25.

S. Pro Aus Blutsauger:

https://gyazo.com/a4ff48c35f314b84a4b4104387b3699d

7 keys gucci gang

Midnight Skullcracker

https://gyazo.com/987e71f692b985debd3c52ef08cf581c

5 keys gucci gang

Strange Invis Watch is 5 keys.

Giger Counter is 2 keys.

Burly Beast is 7 keys.

100 keys is 100 keys.

The last time this sale was calculated, approximately 18 days ago in season 3, this sale was 150 keys.

//

Sale 2:

https://marketplace.tf/items/30937;5;u9

Sold on May 22, 2019 for $230.00 / 1.79 = 128 keys

//

Credits:

Thank you RodneyCopperBottom for providing another sale here,

https://backpack.tf/suggestion/5c8d26b9678072154d3c3e18

Thank you Foamy for correcting my mistake here,

https://backpack.tf/suggestion/5cb2d2c4d38172250552d9b0

Thank you Rasen for providing another sale here,

https://backpack.tf/suggestion/5ce03708678072171417c03f

Thank you whichever moderator will end the pain

https://gyazo.com/3f421abc75814c0871d5e50228a734a8