Sale 1:

Sold for a Purple Confetti Team Captain and 3 keys

(77*0.9) - 3 = 66.3 rounding to 66 keys

http://www.tf2outpost.com/trade/25907785

http://backpack.tf/profiles/76561198001300729?time=1431846000 (May 17th)

http://backpack.tf/profiles/76561198001300729?time=1431932400 (May 18th

Sale 2:

Sold for a Sulphurous Hat of Cards

(94*0.9) = 84.6 rounding to 85 keys

http://www.tf2outpost.com/trade/25607446

http://backpack.tf/profiles/76561198070996875?time=1428994800 (April 14th)

http://backpack.tf/profiles/76561198070996875?time=1429167600 (April 16th)

Sale 3:

Sold with 4 buds (they were 5) for a Smoking Demoman's Fro, a Massed Flies Lucky Shot and a

(72 + 15 + 24)*0.9 - 20 = 79.9 rounding to 80 keys

http://www.tf2outpost.com/trade/25824010

http://backpack.tf/profiles/76561198031385226?time=1430377200 (April 30th)

http://backpack.tf/profiles/76561198031385226?time=1430463600 (May 1st)

Sale 4:

Sold with a Circling Peace Sign Private Eye and a Max’s for an It's A Secret To Everybody Armored Authority

(97*0.9) - 20 - 24 = 43.3 rounding to 43 keys

http://backpack.tf/profiles/76561198065790776?time=1429081200 (April 15th)

http://backpack.tf/profiles/76561198065790776?time=1429167600 (April 16th)

Sale 5:

Sold with a Circling Peace Sign Private Eye, a Max’s and 2 buds (were 10) for a Molten Mallard Horrific Headsplitter

(121*0.9) - 20 - 24 - 10 - 10 = 44.9 rounding to 45 keys

http://backpack.tf/profiles/76561198003793157?time=1429599600 (April 21st)

http://backpack.tf/profiles/76561198003793157?time=1429686000 (April 22nd)

Sale 6:

Sold for a Green Black Hole Dr's Dapper Topper, a Haunted Ghosts Backbiter's Billycock and an Australium Black Box

(38.5 + 20)*0.9 + 19 -1 = 70.65 rounding to 71 keys

http://backpack.tf/profiles/76561198071334162?time=1433055600 (May 31st)

http://backpack.tf/profiles/76561198071334162?time=1433142000 (June 1st)

Sale 7:

Sold with a Pro. Australium RL and 13 keys of stuff for a Vivid Cone and an Australium FAN

(145*0.9) + (13 -1) - 68 -13 = 61.5 rounding to 62 keys

http://backpack.tf/profiles/76561198066271242?time=1426662000 (March 18th)

http://backpack.tf/profiles/76561198066271242?time=1426748400 (March 19th)

Notes:

Mini for the Smoking Demoman's Fro:

Listed at 20 keys on various trades for 2 weeks

http://www.tf2outpost.com/trade/26018089

After not selling at 20 for 2 weeks, the user now has it listed for 15

http://www.tf2outpost.com/trade/26116314

Going with 15 keys

Mini for the Massed Flies Lucky Shot:

Sold for a S. Pro. Gunslinger

24 keys

http://backpack.tf/profiles/76561198031385226?time=1430463600 (May 1st)

http://backpack.tf/profiles/76561198031385226?time=1430636400 (May 3rd)

Mini Mini for the S. Pro. Gunslinger:

2 sold for $57.48 on the SCM on the day of the sale

(57.5/2.4) = 23.9583333 rounding to 24 keys

http://steamcommunity.com/market/listings/440/Strange%20Professional%20Killstreak%20Gunslinger

Mini for the Pro Australium RL:

3 sold for $162 on the SCM on the day of the sale

(162/2.4) = 67.5 rounding to 68 keys

http://steamcommunity.com/market/listings/440/Strange%20Professional%20Killstreak%20Australium%20Rocket%20Launcher

Conclusion:

Sales at 85, 80, 71, 66, 62, 45, 43

45 and 43 are obvious outliers, Mindacos advised me to take the range at 62 to 80.