One step closer to the edge.

https://backpack.tf/item/5006098987

Sale 1) Sold for a Death by Disco Prehistoric Pullover (175 Keys) + Haunted Ghosts Brotherhood of Arms (117 Keys) + Circling TF Logo Legendary Lid (61 Keys)

https://backpack.tf/profiles/76561198119149660#!/compare/1560038400/1560124800

https://backpack.tf/profiles/76561198431135206#!/compare/1560124800/1560211200

https://imgur.com/a/bokBDmf - Capped by the Buyout of 350 Keys

Haunted Ghosts Brotherhood of Arms Mini

https://backpack.tf/suggestion/5d6c8e066780721a274e364c - 117 Keys

Legendary Lid Mini

https://marketplace.tf/items/tf2/30868;5;u11 - Sold for $110 when Keys were ~$1.80 each

https://marketplace.tf/items/tf2/5021;6

110 / 1.80 = 61.1, which rounds to 61 Keys

Sale 2) Sold for a Sunbeams Brotherhood of Arms

https://backpack.tf/profiles/76561198431135206#!/compare/1561075200/1561161600

Sales on the Sunbeams BoA are ~220 and $550; excluding from here.

Sale 3) Sold for 2 Cloudy Moon Troublemaker's Tossle Caps (~138 Keys each) + Disco Beat Down Soldered Sensei + 4 Keys

https://backpack.tf/profiles/76561198269636307#!/compare/1562198400/1562284800

138 + 138 + 49 + 4 = 329, which I'll round to 330 Keys

Tossle Cap Mini

https://backpack.tf/suggestion/5d51e64cd381724b6b751136 - 138 Keys each

Soldered Mini

https://backpack.tf/profiles/76561198156255538#!/compare/1563840000/1563926400 - Sold for 49 Keys

Last suggestion is barely outdated, but this is the only usable sale since.

Sale 4) Sold + 2 Festivizers (~1.5 Keys) + 1 Key for a Burning Flames Rotation Sensation (178.5 Keys) + Subatomic Sucker Slug (140 Keys)

https://backpack.tf/profiles/76561198008994962#!/compare/1562371200/1562544000

178.5 + 140 - 1.5 - 1 = 316, which I'll round to 315 Keys

Rotation Mini

https://backpack.tf/profiles/76561198127717925#!/compare/1564704000/1564790400 - Sold + BS Attendant (14.25 Keys) for a Beams Master's (171.5 Keys)

https://backpack.tf/profiles/76561198008994962#!/compare/1563494400/1563667200 - Sold for a Burning Tossle (160 Keys) + C9 HKC (~39.5 Keys)

https://marketplace.tf/items/tf2/30623;5;u13 - Sold for $350 when Keys were ~$1.84 each

https://marketplace.tf/items/tf2/5021;6

350 / 1.84 = 190.22, which rounds to 190 Keys

Taking 157 - 200, which averages to 178.5 Keys

Blizzardy Storm Attendant Micro

https://backpack.tf/profiles/76561198156315732#!/compare/1564012800/1564099200 - Sold for 12 Keys + ~1.5 Keys of Refined/Items

https://backpack.tf/profiles/76561198127717925#!/compare/1564876800/1564963200 - Sold for 15 Keys

Taking 13.5 - 15, which averages to 14.25 Keys

Burning Flames Troublemaker's Tossle Cap Micro

https://backpack.tf/suggestion/5d5cdec767807239f736563c - 160 Keys

Cloud 9 Hong Kong Cone Micro

https://backpack.tf/profiles/76561198239018976#!/compare/1564358400/1566691200 - Sold for 37 Keys

https://backpack.tf/profiles/76561198286234945#!/compare/1567123200/1567209600 - Sold for 35 Keys

https://backpack.tf/profiles/76561198109451379#!/compare/1566691200/1566864000 - Sold for 35 Keys

https://marketplace.tf/items/tf2/30177;5;u58 - 2 Marketplace sales for $80 when Keys were ~$1.82 each

https://marketplace.tf/items/tf2/5021;6

80 / 1.82 = 43.96, which rounds to 44 Keys

Taking 35 - 44, which averages to 39.5 Keys

Sale 5) Sold for a Burning Flames Reggaelator (174 Keys) + Scorching Flames Rotation Sensation (173 Keys) + Strange GIGER Counter (~11 Keys) + 2 Keys

https://backpack.tf/profiles/76561197978500506#!/compare/1562889600/1562976000

https://backpack.tf/profiles/76561198114522039#!/compare/1562716800/1562889600

174 + 173 + 11 + 2 = 360 Keys

Burning Flames Reggaelator Mini

https://backpack.tf/suggestion/5d6dfea267807244a313573d - 174 Keys

Scorching Flames Rotation Sensation Mini

https://backpack.tf/suggestion/5d6df7a967807244673a4fe5 - 173 Keys

https://backpack.tf/item/7265915117

Sale 6) Sold for 341 Keys + Terror-Watt Tin Capotain (7 Keys) + ~3 Keys of Items

https://backpack.tf/profiles/76561198086948995#!/compare/1566777600/1566950400

341 + 7 + 3 = 351, which I'll round to 350 Keys

Capotain Mini

https://imgur.com/a/2bhCkWi - 2 Sellers at 17 Keys (1 Day, 5 Days) and 2 Sellers at 8 Keys (15 Days, 1 Day)

https://backpack.tf/item/7089001712

https://backpack.tf/item/2030728893

https://backpack.tf/item/2923942905

https://backpack.tf/item/7956124296

Taking 7 Keys for the Capotain

https://backpack.tf/item/5523164849

Sale 7) ?

https://backpack.tf/profiles/76561198118907985#!/compare/1563840000/1564272000

https://backpack.tf/profiles/76561198035334988#!/compare/1564099200/1564272000

Sale 8) ?

https://backpack.tf/profiles/76561198035334988#!/compare/1565481600/1565568000

Sale 9) Sold for 322 Keys

https://backpack.tf/profiles/76561198267963372#!/compare/1565568000/1565654400

https://backpack.tf/profiles/76561198974428230#!/compare/1565568000/1565654400

https://backpack.tf/item/5389366554

Sale 10) Looks like Marketplace

https://backpack.tf/profiles/76561198119149660#!/compare/1565136000/1565481600

https://backpack.tf/profiles/76561198042816251#!/compare/1564790400/1565136000

https://marketplace.tf/items/tf2/30066;5;u13 - Sold for $450 when Keys were $1.80, $425 when Keys were $1.80, and $350 when Keys were $1.81

https://marketplace.tf/items/tf2/5021;6

450 / 1.8 = 250 Keys

425 / 1.8 = 236.11, which rounds to 236 Keys

350 / 1.81 = 193.37, which rounds to 193 Keys

https://imgur.com/a/HW8UW98 - 17 Day Seller at 350 Keys and a 2 Day Seller at 350 Keys

https://backpack.tf/item/5006098987

https://backpack.tf/item/6808049597

Calling the Marketplace sales low and going 315 - 350 Keys. Calling 360 high because of the Sellers and due to removing the 3 low sales.