Bought one for 81 keys pure:

https://backpack.tf/profiles/76561198020981163#!/compare/1641686400/1641772800

Image is more accurate https://imgur.com/a/HybNEmZ

Not so many other recent sales and only few of them are traceable:

1) Previous declined and quite complicated suggestion (credits to The Raging Russian):

https://backpack.tf/profiles/76561198133319499#!/compare/1637193600/1637280000

Seems like 15 keys + Strange Vet's Attire and Strange parted Movember + Terror-watt TC were involved from the first side, and doublespelled Bill + Bucket were involved from the other side.

Found only one and a bit outdated (4 months) sale on TC, which seems like involved 48 keys, but I'm not sure https://backpack.tf/profiles/76561198059812481#!/compare/1630972800/1631145600

On the other side, we have one seller at 115 keys and 4 buyers at 62+ keys https://backpack.tf/stats/Unusual/Team%20Captain/Tradable/Craftable/57, so I think 62 keys could be taken as a basis.

Summing up: 15 pure + 4.18 (Attire) + 1.85 (Movember) + 62 (TC) - 3.2 (Bill's) = rounding to 86 keys. But still quite inaccurate.

2) Sold for duped spelled HG Armored Authority (61 keys) https://backpack.tf/profiles/76561198125655370#!/compare/1632009600/1637884800

Some other untraceable sales:

https://backpack.tf/profiles/76561198113835970#!/compare/1637366400/1637452800

https://backpack.tf/profiles/76561199017434769#!/compare/1637193600/1637798400

https://backpack.tf/profiles/76561198019291469#!/compare/1634428800/1636848000

Buyers on Bucket are at 73.5+ and a seller on 100 atm (84 untill today)

Summing up:

accurate 81

Inaccurate 86

61, but might exclude as long as buyers are higher then this atm (73.5+)

So, taking 81 flat, as it seems the most clean to me.

All thanks to The Real Slim Strange for providing links to other Buckets!