Requested.

http://backpack.tf/item/3121268785

Sale 1) Sold for a Duped Kill-a-Watt Brain Bucket + Duped Bubbling Shooter's Tin Topi + Earbuds (~2 Keys)

http://backpack.tf/profiles/76561198048851745#!/compare/1467504000/1467590400 - Seller's Backpack

https://backpack.tf/profiles/76561198054384475#!/compare/1467331200/1467590400 - Buyer's Backpack

Likely fits in the range.

Sale 2) Sold for an Overclocked Grimm Hatte (23 Keys)

http://backpack.tf/profiles/76561198054384475#!/compare/1467849600/1467936000

Low Outlier, given the buyer in the Classified Ads at 24 Keys.

Sale 3) Sold for a Steaming Hat With No Name + 2 Keys

http://backpack.tf/profiles/76561198136485949#!/compare/1467849600/1467936000

Likely fits in the range.

Sale 4) Sold for a Kill-a-Watt Front Runner (36 Keys)

http://backpack.tf/profiles/76561198064779579#!/compare/1468108800/1468195200

http://www.tf2outpost.com/trade/28327321 - Capped by the Buyout of 35 Keys

Sale 5) Sold for 28 Keys

http://backpack.tf/profiles/76561198028490870#!/compare/1473811200/1474070400 - Seller's Backpack

http://backpack.tf/profiles/76561198241272522#!/compare/1473984000/1474070400 - Buyer's Backpack

Turtle sold the Whoopee to Bipolar for 28 Keys, and then those 28 Keys + the other 8 you see in the Seller's Backpack were for the Phononaut.

http://backpack.tf/profiles/76561198055617854#!/compare/1473984000/1474070400 - The Seller of the Phononaut received 36 Keys.

Sale 6) Sold for a Power Surge Prince Tavish's Crown (23 Keys) + 6 Keys

http://backpack.tf/profiles/76561198241272522#!/compare/1474243200/1474329600

23 + 6 = 29 Keys

Crown Mini

http://www.tf2outpost.com/trade/28499520 - Seller for 23 Keys for 5 Days.