Resuggestion with consideration to additional proof.

Sale 1:

Sold for 23 keys

http://backpack.tf/profiles/76561198090737788#!/compare/1475366400/1475452800

Sale 2:

Sold for 20 keys pure

Buyer's backpack before/after - http://backpack.tf/profiles/76561198286234945#!/compare/1475798400/1475884800

Seller's backpack before/after - http://backpack.tf/profiles/76561198159664219#!/compare/1475798400/1475884800

Sale 3:

Sold with Pro KS Aussie Ambassador (20) for Pro KS Aussie Sniper Rifle (34) + 2 keys, 16 keys total

Not using, bulk sale, but this sale supports drop

http://backpack.tf/profiles/76561198090737788#!/compare/1475107200/1475366400

Ambassador:

https://i.gyazo.com/4e03aaccc9c8761468490d901a698e74.png

Sniper Rifle:

https://i.gyazo.com/225d03f8a9d69800d844f625938997f1.png

Sale 4:

Bulk

http://backpack.tf/profiles/76561198088079103#!/compare/1473379200/1473465600

Sale 5:

Bulk

http://backpack.tf/profiles/76561198114243080#!/compare/1472860800/1473120000

Sale 6:

Sold for Aces High Bot Dogger (22 keys) + 2 keys pure, 24 total

http://backpack.tf/profiles/76561198015384426#!/compare/1475884800/1475971200

Sale 7:

Sold for Duped Disco Beat Down Bonk Helm (21 key) + ~3 keys in sweets 24 keys total

http://backpack.tf/profiles/76561198155659357#!/compare/1473033600/1473206400

Mini for Bonk Helm:

21 keys pure

http://backpack.tf/profiles/76561198045312207#!/compare/1475625600/1475798400

Sale 8:

Sold with Spec KS Aussie SMG (7.5 keys) for KS Aussie Sniper Rifle (27), 20 keys total

http://backpack.tf/profiles/76561198196762265#!/compare/1472428800/1472515200

SMG:

https://i.gyazo.com/f473e686613c42977ca9ce55676464e8.png

Sniper Rifle:

https://i.gyazo.com/a8475b85d1503b1d8f9ec27c8fa75cf1.png

Sale 9:

Sold for Green Energy Bootleg Base Metal Billycock (25 keys)

http://backpack.tf/profiles/76561198147100597#!/compare/1472515200/1472688000

Sales at 20k x2, 23k x1, 24k x2, 25 x1

2 young sellers at 22 keys at classies

Taking range 20-25.

Thanks to Pampick - http://backpack.tf/profiles/76561198053700606 for help with finding additional proof.