Resuggesting, thanks Xergoyf.

Sales

Sale 1: Sold for 90 keys

https://backpack.tf/profiles/76561198083134207#!/compare/1599436800/1599523200

https://backpack.tf/profiles/76561198216730925#!/compare/1599436800/1599523200

Sale 2: Sold for 85 keys

https://backpack.tf/profiles/76561198216730925#!/compare/1599955200/1600041600

https://backpack.tf/profiles/76561198212566375#!/compare/1599782400/1600041600

Sale 3: Sold with 47 keys + Australium Axtinguisher + about 4 keys~ in other sweets for CMoon Surgeon's Stahlhelm

https://backpack.tf/profiles/76561198390580688#!/compare/1596067200/1596153600

https://backpack.tf/profiles/76561198083134207#!/compare/1596067200/1596153600

Better used for the CMoon.

Sale 4: Sold for 77 keys

https://backpack.tf/profiles/76561198079259544#!/compare/1597881600/1597968000

https://backpack.tf/profiles/76561198403404710#!/compare/1597881600/1597968000

Sale 5: https://imgur.com/a/vuMjYCA Both the operation breakout keys I used + normal keys were valued at scm price, so it should be safe to say I paid 161.65 for it, 161.65/2.41 (keys on there w/ bonus) = ~67 keys.

Sale 6: Sold for DaD Napper's Respite + 8 keys

https://backpack.tf/profiles/76561198163615254#!/compare/1600473600/1600560000

https://backpack.tf/profiles/76561198115233455#!/compare/1598918400/1602374400

Going to use for the Napper's.

Exchanges with marketplace, tradeit,and stn.

https://backpack.tf/item/7201801150

https://backpack.tf/item/3606836441

https://backpack.tf/item/3272861759

Marketplace sales

https://marketplace.tf/items/tf2/616;5;u90

Nothing recent.

Current Classifieds

https://backpack.tf/classifieds?item=Surgeon%27s%20Stahlhelm&quality=5&tradable=1&craftable=1&australium=-1&particle=90&killstreak_tier=0

https://gyazo.com/cf8ab506d5ff5e7a583dbfa9a298e983

Summary

Sales at 67, 77, 85, and 90.

Conclusion

Cutting one on both sides as outliers, excluding 67 and 90.

Going with 77-85 here.

Take it easy.