Sale 1:

Sold for Cloud 9 Noble (24) + 3 keys

http://www.tf2outpost.com/trade/28545689 - Deleted B/O

Seller: http://backpack.tf/profiles/76561198004517334#!/compare/1477353600/1477440000

Buyer: http://backpack.tf/profiles/76561198095446085#!/compare/1477008000/1478822400

X = 27

Sale 2:

Sold for Ooze Scotch (28)

http://www.tf2outpost.com/trade/28488623 - B/O of 25

Seller: http://backpack.tf/profiles/76561198156255538#!/compare/1473897600/1473984000

Buyer: http://backpack.tf/profiles/76561198137255950#!/compare/1473984000/1474070400

X = 25 (Capped by B/O)

Sale 3:

Quicksold for 22 keys

No outpost

Seller: http://backpack.tf/profiles/76561198088878793#!/compare/1474502400/1474588800

Buyer: http://backpack.tf/profiles/76561197997500296#!/compare/1474416000/1474588800

The seller owned the item for about a day

X = 22

Sale 4:

Sold with 6 keys for Spec. KS Aussie Scattergun (28)

No outpost

Seller: http://backpack.tf/profiles/76561197997500296#!/compare/1476489600/1476576000

Buyer: http://backpack.tf/profiles/76561198004517334#!/compare/1476489600/1476576000

X = 22

Sales at:

27

25

22 (2x)

No current sellers

22 has been proven to quicksell, excluding 22.

Going with 25-27