One year old price.

Mini for Pumpkin Party Sir Pumpkinton and Nuts n' Bolts Legendary Lid.

Unusuable sale 1:

https://backpack.tf/item/1657266005

https://backpack.tf/profiles/76561199101484822#!/compare/1608336000/1608422400

https://backpack.tf/profiles/76561198149459336#!/compare/1608422400/1608508800

1:1 for Pumpkin Party Sir Pumpkinton.

Unusuable sale 2:

https://backpack.tf/item/1657266005

https://backpack.tf/profiles/76561198085880346#!/compare/1606435200/1606608000

https://backpack.tf/profiles/76561198228991628#!/compare/1606521600/1606608000

This + 7 keys for Nuts n' Bolts Legendary Lid.

Sale 1:

https://backpack.tf/item/1657266005

https://backpack.tf/profiles/76561198021055079#!/compare/1605139200/1605225600

https://backpack.tf/profiles/76561198338460908#!/compare/1605139200/1605225600

46 keys.

Sale 2:

https://backpack.tf/item/1657266005

https://backpack.tf/profiles/76561198085880346#!/compare/1607126400/1607385600

https://backpack.tf/profiles/76561198832634596#!/compare/1607212800/1607299200

28 keys + Veno Shock Taunt: The Fubar Fanfare + Kill-a-Watt Barnstormer.

28 + 6 + 12 = 46 keys.

Mini for Veno Shock Taunt: The Fubar Fanfare:

https://backpack.tf/suggestion/6001814011b5611b2c714136

6.25 keys, rounded to 6.

Mini for Kill-a-Watt Barnstormer:

https://backpack.tf/item/2228128303

https://backpack.tf/profiles/76561199080033728#!/compare/1606780800/1606867200

https://backpack.tf/profiles/76561198832634596#!/compare/1606780800/1606867200

12 keys.

Sale 3:

https://backpack.tf/item/1657266005

https://backpack.tf/profiles/76561198832634596#!/compare/1607731200/1607817600

https://backpack.tf/profiles/76561198169756327#!/compare/1607644800/1607817600

1:1 for Disco Beat Down Hat With No Name.

51 keys.

Mini for Disco Beat Down Hat With No Name:

Sale 1:

https://backpack.tf/item/7957069895

https://backpack.tf/profiles/76561198137564765#!/compare/1609372800/1609459200

https://backpack.tf/profiles/76561198176593866#!/compare/1609200000/1609459200

45 keys.

Sales 2 & 3:

https://marketplace.tf/items/tf2/631;5;u62

Nov 7, 2020: $62.05 - $62.05 / $1.81 = 34.28 keys

Dec 2, 2020: $99.99 - $99.99 / $1.76 = 56.81 keys

Exclude 34 keys: https://gyazo.com/3936e42f8aac77774aca0bfc2ffa840b

45-57 has a median of 51 keys. This corresponds with a seller at 51 keys: https://gyazo.com/c3b4ac467ac664a450e3513021b9677c

I am not excluding 57 because the listing is recent.

Sale 4:

https://backpack.tf/item/1657266005

https://backpack.tf/profiles/76561198169756327#!/compare/1607904000/1608163200

https://backpack.tf/profiles/76561198149459336#!/compare/1608163200/1608249600

None of the keys line up. It may be 50 keys, which is already included in the range.

Conclusion:

Excluding the items that this suggestion is a mini for, we have sales at 51 and 46. Using all for a range of 46-51.