It's Steaming, Watson!

http://backpack.tf/item/863824540

Sale 1) Sold + ~1 Key of Items for a FT Energy Orb Woodsy Widowmaker (17 Keys)

http://backpack.tf/profiles/76561198185224947#!/compare/1486684800/1487116800 - Buyer's Backpack

17 - 1 = 16 Keys

http://backpack.tf/item/799777850

Sale 2) Sold + 2 Keys for a Disco Beat Down FR-0 (14.5 Keys)

http://backpack.tf/profiles/76561198189725409#!/compare/1483488000/1483574400

Low Outlier.

FR-0 Mini

http://backpack.tf/suggestion/58d9d104c4404568f12f4100 - 14.5 Keys

Sale 3) Sold for a Kill-a-Watt Full Metal Drill Hat

http://backpack.tf/profiles/76561198079525890#!/compare/1485388800/1485475200

Fits in the range.

http://backpack.tf/item/1571750267

Sale 4) Sold for an Aces High Soldier's Slope Scopers (16 Keys) + ~2 Keys of Items

http://backpack.tf/profiles/76561198260271932#!/compare/1485129600/1485302400

16 + 2 = 18 Keys

Scopers Mini

http://backpack.tf/profiles/76561198177179669#!/compare/1483315200/1484006400 - Sold + 1 Key for a Blizzardy Storm Luchadore (~17 Keys)

Luchadore Micro

http://backpack.tf/stats/Unusual/Large%20Luchadore/Tradable/Craftable/30 - Seller at 17 Keys.

Imgur isn't working right now, so I'll comment an image of that Seller tomorrow.