Sale 1:

Sold for 24 keys (buyer’s backpack)

No outpost

Seller: http://backpack.tf/profiles/76561198192602363#!/compare/1488931200/1489017600

Buyer: http://backpack.tf/profiles/76561198202658467#!/compare/1489017600/1489104000

X = 24

Sale 2:

Sold for 20 keys

http://www.tf2outpost.com/trade/28973426 - B/O of 20

Seller: http://backpack.tf/profiles/76561198067575136#!/compare/1492300800/1492387200

Buyer: http://backpack.tf/profiles/76561198369860557#!/compare/1492387200/1492473600

X = 20

Sale 3:

Sold for Cool Factory New Blitzkrieg SMG

Seller: http://backpack.tf/profiles/76561198369860557#!/compare/1492473600/1492560000

Buyer: http://backpack.tf/profiles/76561198253355545#!/compare/1492560000/1492646400

Can be used to update the SMG

Sale 4:

Bulk for Beams Hat With No Name

Seller: http://backpack.tf/profiles/76561198025431788#!/compare/1489795200/1489881600

Buyer: http://backpack.tf/profiles/76561198096389539#!/compare/1489795200/1489881600

Sale 5:

Bulk for Circling Heart Rotation

Seller: http://backpack.tf/profiles/76561198044971939#!/compare/1489536000/1489708800

Buyer: http://backpack.tf/profiles/76561198085269574#!/compare/1489536000/1489622400

Sale 6:

Bulk for Terror-Watt Polar Pullover

Seller: http://backpack.tf/profiles/76561198085269574#!/compare/1490400000/1490486400

Buyer: http://backpack.tf/profiles/76561198086793593#!/compare/1490400000/1490486400

Sale 7:

Bulk for Strange Nebula Head Full of Hot Air

Seller: http://backpack.tf/profiles/76561198202658467#!/compare/1489104000/1489190400

Buyer: http://backpack.tf/profiles/76561198127971615#!/compare/1489017600/1489190400

Sale 8:

Bulk for keys

Seller: http://backpack.tf/profiles/76561198127971615#!/compare/1491782400/1491868800

Buyer: http://backpack.tf/profiles/76561198067575136#!/compare/1491782400/1491868800

Sellers:

19.35 keys:

http://i.imgur.com/3WkqcQB.png - 1 day

http://backpack.tf/u/76561198304138933

20 keys:

http://i.imgur.com/NkS3oQc.png - 2 days

http://backpack.tf/u/76561198344933095

http://i.imgur.com/lj3Pqh2.png - 5 days

http://backpack.tf/u/76561198067575136

http://www.tf2outpost.com/trade/28973426

23 keys:

http://i.imgur.com/5czxhRx.png - 30 days

http://backpack.tf/u/76561198096389539

http://www.tf2outpost.com/trade/28873364

25 keys:

http://i.imgur.com/q34VFlV.png - 2 months

http://backpack.tf/u/76561198011321852

http://www.tf2outpost.com/trade/28997856

http://i.imgur.com/sb0TE2v.png - 21 days

http://backpack.tf/u/76561198054758757

26 keys:

http://i.imgur.com/dAgqTOk.png - 25 days

http://backpack.tf/u/76561198316071886

30 keys:

http://i.imgur.com/fKysB0x.png - 5 days, most likely re-listed at some point

http://backpack.tf/u/76561198043936328

http://www.tf2outpost.com/trade/28876048 - 4 weeks here

Offers:

http://www.tf2outpost.com/trade/24633534 - 2 years

http://backpack.tf/u/76561198050582650

Selling as set:

http://www.tf2outpost.com/trade/28718635 - 3 months

http://backpack.tf/u/76561198008212178

Sales at:

20

24

Going with 20-24.