Practice makes perfect, or close to it anyways.

Sale 1: Sold for 20 keys

https://backpack.tf/profiles/76561198177872379#!/compare/1581292800/1581379200

https://backpack.tf/profiles/76561198133143566#!/compare/1581206400/1581292800

Sale 2: Quicksold? Unknown

https://backpack.tf/profiles/76561198337734785#!/compare/1583539200/1583625600

https://backpack.tf/profiles/76561198319103731#!/compare/1583712000/1549411200

Sale 3: Sold for Stormy Storm El Jefe + Genuine Tomb Readers painted white (1.85 keys)

https://backpack.tf/profiles/76561198339706990#!/compare/1585526400/1585699200

https://backpack.tf/profiles/76561198451469561#!/compare/1585440000/1586649600

15 + 1.85 = 16.85 rounding to 17 keys

Open Suggestion for the El Jefe at 15 keys:

https://backpack.tf/suggestion/5eb712ffb019193ff4258918

Sale 4: Unknown, was sold to a quickbuyer however.

https://backpack.tf/profiles/76561198985910282#!/compare/1586563200/1586736000

https://backpack.tf/profiles/76561198451469561#!/compare/1585440000/1586649600

Sale 5, 6, 7 & 8: Marketplace sales

https://marketplace.tf/items/tf2/105;5;u30

55.56 on March 6, 2020

https://backpack.tf/item/619622058

55.56/1.71 = 32.49 rounding to 32 keys

38.99 on April 16, 2020

38.99/1.78 = 21.9 rounding to 22 keys

26 on April 19, 2020

26/1.79 = 14.52 rounding to 15 keys

49.99 on May 2, 2020

https://backpack.tf/item/736668897

49.99/1.87 = 26.73 rounding to 27 keys

Classifieds:

https://gyazo.com/80a0c461746502147fc96252b8d51347

Multiple sales, are at 15, 17, 20, 22, 27, and 32.

Due to buyers at 16, I will say 15 is low. There is a seller at 30 keys, for 8 days, I will say 32 is high.

Taking a wide range of 17-27 keys here.