Thanks Roller :)

Sale 1:

Sold with a Cloud 9 Virtual Viewfinder and a Cloudy Moon Gym Rat for a Disco Beat Down Virtual Viewfinder

(223*0.9) - 23 - 116 = 61.7 rounding to 62 keys

http://www.tf2outpost.com/trade/25649265

http://backpack.tf/profiles/76561198043781630?time=1429340400 (April 18th)

http://backpack.tf/profiles/76561198043781630?time=1429426800 (April 19th)

Sale 2: (outlier)

Sold with a Prof. S. F. Holy Mackerel for a Disco Beat Down Milkman

(44*0.9) - 8 = 31.6 rounding to 32 keys

http://backpack.tf/profiles/76561198159595971?time=1431586800 (May 14th)

http://backpack.tf/profiles/76561198159595971?time=1431673200 (May 15th)

Sale 3:

Sold for a Memory Leak Conquistador, a Nuts and Bolts Swagman's Swatter, an Overclocked Tippler's Tricorne, and a Circling Peace Sign Janissary Ketch

(13 + 15 + 11 + 17)*0.9 = 50.4 rounding to 50 keys

http://backpack.tf/profiles/76561198059216451?time=1426575600 (March 17th)

http://backpack.tf/profiles/76561198059216451?time=1426662000 (March 18th)

[Sale #4] Sold for Duped Beams Jumper's Jeepcap (53 Keys) + Sweets (~7 Keys) w/ Flames Hard Counter (18 Keys) ~42 Keys

http://backpack.tf/profiles/76561198105949351?time=1433478676

http://backpack.tf/profiles/76561198105949351?time=1433574000

Duped Beams Jumper:

Sold for Knifestorm Pith (36 Keys) + Earbuds (3 Keys) + TW Fukaa (10 Keys) + Sweets (~4 Keys) ~53 Keys

http://backpack.tf/profiles/76561198010082723?time=1432537200

http://backpack.tf/profiles/76561198010082723?time=1432636411

[Sale #5] Sold for C9 Marauder (24 Keys) + DP AA (24 Keys) ~48 Keys

http://backpack.tf/profiles/76561198113677851?time=1433660400

http://backpack.tf/profiles/76561198113677851?time=1433746800

DP AA:

Sold for Level 1 Black Max ~24 Keys

http://backpack.tf/profiles/76561198079118378?time=1433538167

http://backpack.tf/profiles/76561198079118378?time=1433574000

Notes:

Buyouts:

http://www.tf2outpost.com/trade/25953907 - 44 Keys - 1 day

http://www.tf2outpost.com/trade/25664689 - 45 Keys - 4 days

http://www.tf2outpost.com/trade/26165765 - 50 Keys - 1 day ago

http://www.tf2outpost.com/trade/25996689 - 50 Keys - 8 days

http://www.tf2outpost.com/trade/25955763 - 50 Keys - 5 days

Mini for the Cloudy Moon Gym Rat: ~23

http://backpack.tf/vote/id/55648db3ba8d8844658b459e

Mini for the Prof. S. F. Holy Mackerel: ~8

2 sold for $15.80 on the SCM on the day of the sale

(15.8/1.9) = 8.31578947 rounding to 8 keys

http://steamcommunity.com/market/listings/440/Strange%20Professional%20Killstreak%20Festive%20Holy%20Mackerel

Mini for the Disco Beat Down Milkman: ~44

http://backpack.tf/vote/id/55648e1ab98d885d2d8b45ae

Mini for the Circling Peace Sign Janissary Ketche: ~13

Seller for 13 keys http://www.tf2outpost.com/trade/25976851

Mini for the Overclocked Tippler's Tricorne: ~14

I can’t find any recent sales that aren’t outliers, using the current price.

Conclusion:

I would not use sale 1 as errors often happen when it's like 3:1, 4:1 or x<1:1

Although Buyouts are quick, this actually shows that different traders are looking for the same buyout, which in this case, 50. I wouldn't include 62 Keys.

42-50 Keys seems fit here.