Four month old price.

Sale 1:

https://marketplace.tf/items/tf2/30120;5;u61

January 5, 2021: $29.99 - $29.99 / $2.12 = 14.15 keys

Sale 2:

https://marketplace.tf/items/tf2/30120;5;u61

October 23, 2020: $29.99 - $29.99 / $1.86 = 16.12 keys

Sale 3:

https://backpack.tf/item/7957169173

https://backpack.tf/profiles/76561198127045035#!/compare/1603411200/1603497600

https://backpack.tf/profiles/76561198345436872#!/compare/1603411200/1603497600

Bulk for Searing Plasma Patriot Peak. Used there.

Sale 4:

https://backpack.tf/item/7957169173

https://backpack.tf/profiles/76561198249609772#!/compare/1604102400/1604275200

https://backpack.tf/profiles/76561198097743466#!/compare/1603756800/1604188800

Untraceable.

Sale 5:

https://backpack.tf/item/2208514531

https://backpack.tf/profiles/76561198148712143#!/compare/1606003200/1606089600

https://backpack.tf/profiles/76561198376879464#!/compare/1606003200/1606089600

14 keys + Strange Beggar's Bazooka.

Valuing Beggar's at 12 ref: https://gyazo.com/0ebacaced322c769801c3b84ee661459

14.2 keys, rounded to 14.

Sale 6:

https://backpack.tf/item/2208514531

https://backpack.tf/profiles/76561199037910054#!/compare/1606780800/1606867200

https://backpack.tf/profiles/76561198349986297#!/compare/1606780800/1606867200

1:1 for Circling TF Logo Antarctic Eyewear.

Mini for Circling TF Logo Antarctic Eyewear:

https://marketplace.tf/items/tf2/30977;5;u11

Nov 9, 2020: $34 - $34 / $1.80 = 18.89 keys

Dec 12, 2020: $39.99 - $39.99 / $1.89 = 21.16 keys

19-21 keys, 20 keys median.

Sale 7:

https://backpack.tf/item/2208514531

https://backpack.tf/profiles/76561198349986297#!/compare/1606780800/1606953600

https://backpack.tf/profiles/76561198253735282#!/compare/1606780800/1606867200

1:1 for Searing Plasma Vampire Vanquisher.

https://backpack.tf/suggestion/60016d7f8ea38c64277ee7d5

13 keys.

Sale 8:

https://backpack.tf/item/2208514531

https://backpack.tf/profiles/76561198253735282#!/compare/1608681600/1608768000

https://backpack.tf/profiles/76561199025158544#!/compare/1608681600/1608768000

Untraceable.

Sale 9:

https://backpack.tf/item/2208514531

https://backpack.tf/profiles/76561199025158544#!/compare/1608768000/1608854400

https://backpack.tf/profiles/76561198851597200#!/compare/1608595200/1608768000

Not obvious what the removed keys in the buyer's inventory went towards. Untraceable in the seller's inventory.

Sale 10:

https://backpack.tf/item/2208514531

https://backpack.tf/profiles/76561198851597200#!/compare/1608854400/1608940800

https://backpack.tf/profiles/76561198286956154#!/compare/1608508800/1608940800

16 keys.

Conclusion:

Astrostuck-tier hats are a pain to price. We have sales at 14, 16 (x2), 14, 20, and 13. 13-20 is too wide and it's the only real outlier here. Every other sale are within a key of each other. Going to go with 13-16 keys.