Sale 1:

Sold for 24 keys (ID’s match)

Seller: https://backpack.tf/profiles/76561198037693798#!/compare/1524960000/1525219200

Buyer: https://backpack.tf/profiles/76561198044157063#!/compare/1525046400/1525737600

X = 24

Sales 2 & 3:

Sold for $45 twice on marketplace.tf

https://marketplace.tf/items/30863;5;u16

45/1.99 = ~22.6

45/1.97 = ~22.8

X = 23 (2x)

Sale 4:

Sold for 20 keys

Seller: https://backpack.tf/profiles/76561198141054773#!/compare/1526256000/1526342400

Buyer: https://backpack.tf/profiles/76561198267199243#!/compare/1526256000/1526342400

X = 20

Sale 5:

Sold for 18 keys

Seller: https://backpack.tf/profiles/76561198310144372#!/compare/1521676800/1521763200

Buyer: https://backpack.tf/profiles/76561198037693798#!/compare/1521763200/1521849600

Bot.tf confirms: https://i.imgur.com/S1HjvP7.png

X = 18

Sale 6:

Sold for 16 keys + 16 ref

Seller: https://backpack.tf/profiles/76561198337734785#!/compare/1523750400/1523836800

Buyer: https://backpack.tf/profiles/76561198171383322#!/compare/1523750400/1523836800

X = 17

Sale 7:

Sold for 14 keys + 13 ref to a bot

Seller: https://backpack.tf/profiles/76561198056842766#!/compare/1525824000/1525996800

Buyer: https://backpack.tf/profiles/76561198385940902#!/compare/1525737600/1525824000

Bot.tf confirms: https://i.imgur.com/S1HjvP7.png

X = 14

Sale 8:

Sold for 14 keys + 10 ref to a bot

https://backpack.tf/item/5883047273 - Seller is untraceable, probably private.

Buyer: https://backpack.tf/profiles/76561198310144372#!/compare/1521417600/1521504000

Bot.tf confirms: https://i.imgur.com/S1HjvP7.png

X = 14

Sale 9:

Sold for Dead Presidents Beak

Seller: https://backpack.tf/profiles/76561198060375373#!/compare/1525392000/1525478400

Buyer: https://backpack.tf/profiles/76561198387330854#!/compare/1525305600/1525478400

no.

Sale 10:

Sold with Aus SMG for Cloud 9 Merryweather

Seller: https://backpack.tf/profiles/76561198387330854#!/compare/1525478400/1525564800

Buyer: https://backpack.tf/profiles/76561198024925599#!/compare/1525478400/1525651200

Should be used on the Merry.

Sale 11:

Bulk for Scorching Raincatcher

Seller: https://backpack.tf/profiles/76561198044157063#!/compare/1526342400/1526428800

Buyer: https://backpack.tf/profiles/76561198018528305#!/compare/1526342400/1526428800

Sellers:

16 keys:

https://i.imgur.com/dP8V2C9.png

https://backpack.tf/item/6138553059

https://backpack.tf/item/6797583802

https://backpack.tf/item/6196107818

17 keys:

https://i.imgur.com/HGpE4ML.png

https://backpack.tf/item/5883047273

Sales at:

14 (2x)

17

18

20

23 (2x)

24

Most sales are significantly higher than the current sellers, so a large range might be necessary here.

Gonna exclude 23 and 24, as they appear to be way too high.

Going with 14-20.

https://backpack.tf/profiles/76561198024925599#!/compare/1528156800/1528243200

https://backpack.tf/profiles/76561198337734785#!/compare/1528156800/1528243200

one of the 16 key sellers sold to a quickbuyer, most likely for 14 keys.