Going down

https://backpack.tf/item/5577134245

Sale 1) Bulk sale for a Burning Flames Brotherhood of Arms

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

Sale 2) Sold for $199.99 when Keys were ~$1.84 each

https://marketplace.tf/items/tf2/30066;5;u8

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

199.99 / 1.84 = 108.69, which rounds to 109 Keys

Sale 3) Sold for $252 when Keys were ~$1.81 each

https://backpack.tf/profiles/76561198240433090#!/compare/1562716800/1564876800

https://backpack.tf/profiles/76561198336661918#!/compare/1563753600/1564358400

https://marketplace.tf/items/tf2/30066;5;u8

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

252 / 1.81 = 139.22, which rounds to 139 Keys

Sale 4) Sold for $220 when Keys were ~$1.82 each

https://backpack.tf/profiles/76561198336661918#!/compare/1566777600/1567209600

https://backpack.tf/profiles/76561198150637341#!/compare/1533081600/1567296000

https://marketplace.tf/items/tf2/30066;5;u8

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

220 / 1.82 = 120.88, which rounds to 121 Keys

https://backpack.tf/item/6128592959

Sale 5) Sold for $293.05 when Keys were ~$1.81 each

https://backpack.tf/profiles/76561198103833545#!/compare/1564272000/1564790400

https://marketplace.tf/items/tf2/30066;5;u8

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

293.05 / 1.81 = 161.91, which rounds to 162 Keys

High outlier.

https://backpack.tf/item/5954836558

Sale 6) Sold for a Strange Purple Energy Rotation Sensation (94 Keys)

https://backpack.tf/profiles/76561198072164101#!/compare/1560384000/1560470400

The suggestion for the Rotation was made a week before this sale occurred, so I'm taking 94 Keys.

Rounding to 95 Keys

Sale 7) Sold for a Purple Energy Flamboyant Flamenco

https://backpack.tf/profiles/76561198410760897#!/compare/1562544000/1562630400

Used it for the Flamenco here -> https://backpack.tf/suggestion/5d5b24556780725b2f6ef53f

Sale 8) ?

https://backpack.tf/profiles/76561197994697258#!/compare/1565136000/1565222400

https://backpack.tf/profiles/76561198056271176#!/compare/1565222400/1565308800