Sale 1:

https://backpack.tf/profiles/76561198991679742#!/compare/1589241600/1589328000

https://backpack.tf/profiles/76561198448830963#!/compare/1589068800/1589241600

untrace

Sale 2:

https://backpack.tf/profiles/76561198448830963#!/compare/1590537600/1590624000

https://backpack.tf/profiles/76561198114680675#!/compare/1590105600/1590710400

Untrace

sale 3:

https://backpack.tf/profiles/76561198164721898#!/compare/1586304000/1586390400

https://backpack.tf/profiles/76561198089821201#!/compare/1585958400/1586390400

Bulk

Sale 4:

https://backpack.tf/profiles/76561198448830963#!/compare/1590616800/1590703200

https://backpack.tf/profiles/76561198144957339#!/compare/1590537600/1590624000

Sold for ~4.25 keys

sale 5:

https://marketplace.tf/items/tf2/1119;5;u3032

$9.72 / $1.69 = 5.75 keys <--- https://backpack.tf/item/2707182368

$9.4 / $1.79 = 5.25 keys <--- https://backpack.tf/item/4081676528

$9.5 / $1.79 = 5.31 keys <--- https://backpack.tf/item/8366301681

$9.6 / $1.79 = 5.36 keys

$9 / $1.88 = 4.79 keys <---- https://backpack.tf/item/2854151654 | https://bot.tf/stats/listings/4O9LKOQQ B/O of 4 keys, capping

$6.55 / $1.96 = 3.34 keys <--- https://backpack.tf/item/3133056340

Total sales @:

3.35, 4, 4.25, 5.25, 5.3, 5.35, 5.75 keys

buyers up to ~3.35 keys,

considering capped sale,

taking 4 - 5.35 keys.