Sale 1:

Sold for Green Black Hole Big Chief (Mini at 59 below) + 1 key

https://i.imgur.com/dwG03IJ.png - B/O of 59

Seller: https://backpack.tf/profiles/76561197969363424#!/compare/1503100800/1503187200

Buyer: https://backpack.tf/profiles/76561198062329277#!/compare/1503187200/1503273600

X = 59 (Capped by B/O)

Sale 2:

Sold for Scorching Backbiter’s Billycock (Suggestion at 59)

http://www.tf2outpost.com/trade/29394832 - B/O of 75

Seller: https://backpack.tf/profiles/76561198071491128#!/compare/1507680000/1507766400

Buyer: https://backpack.tf/profiles/76561198040604243#!/compare/1507420800/1507766400

X = 59

Sale 3:

Sold with ~6 keys in pure/items for Time Warp Barnstormer + Spec. KS Aussie Blut (7)

http://www.tf2outpost.com/trade/29396305 - B/O of 66

Seller: https://backpack.tf/profiles/76561198040604243#!/compare/1507766400/1507939200

Buyer: https://backpack.tf/profiles/76561198120672630#!/compare/1507852800/1507939200

No mini available on the Barnstormer. Should be used on that instead.

Scorching Backbiter’s Billycock:

https://backpack.tf/suggestion/59e94e72cf6c75363373d2d6

Green Black Hole Big Chief Mini:

Sold for $119.99 on Marketplace.tf

https://i.imgur.com/flnl6OU.jpg - Was willing to take 59 keys

https://marketplace.tf/items/309;5;u71;strange

https://backpack.tf/item/1671939327

119.99/1.95 = ~61.53

X = 59 (Capped by B/O)

The hat also sold for $86, but the amount of time it was listed for cannot be properly determined, so I will exclude it.

Sellers:

72 keys:

https://i.imgur.com/THpAPdq.png - 5 days

Sales at:

59 (2x)

Going with 59 flat.