Sales 1 & 2:

Sold for $33 and $40 on Marketplace.tf

https://marketplace.tf/items/1112;5;u3003

https://backpack.tf/item/6421693771

Can’t find the $33 one.

40/1.98 = ~20.2

33/1.9 = ~17.4

X = 17 and 20

Sale 3:

Sold for 15 keys

Seller: https://backpack.tf/profiles/76561198309332284#!/compare/1514332800/1514419200

Buyer: https://backpack.tf/profiles/76561198324290571#!/compare/1514332800/1514419200

X = 15

Sale 4:

Bulk for Scorching Western Wear

Seller: https://backpack.tf/profiles/76561198061082936#!/compare/1515110400/1515196800

Buyer: https://backpack.tf/profiles/76561198174203179#!/compare/1515024000/1515110400

Sale 5:

Bulk for Phantasm Brewed Victory

Seller: https://backpack.tf/profiles/76561198173027559#!/compare/1512000000/1512086400

Buyer: https://backpack.tf/profiles/76561198374485308#!/compare/1511913600/1512086400

Sellers:

17 keys:

https://i.imgur.com/govUzxn.png - 13 days

18 keys:

https://i.imgur.com/tNovZNe.png - 1 day

20 keys:

https://i.imgur.com/2wiSbtI.png - 4 days

25 keys:

https://i.imgur.com/UVzuFrF.png - 15 days

29 keys:

https://i.imgur.com/lA24Ehu.png - 1 month

Sales at:

15

17

20

Going with 15-20.