Sale 1)

Sold for smoking veil

http://backpack.tf/profiles/76561197969015493?time=1428130800 (April 4th)

http://backpack.tf/profiles/76561197969015493?time=1428562800 (April 9th)

Veil sold for pure, no overpay needed. 60 keys.

Mini on veil:

Sold for 60 keys pure

http://backpack.tf/profiles/76561197983196231?time=1429858800 (April 24th)

http://backpack.tf/profiles/76561197983196231?time=1432018800 (May 19th)

http://backpack.tf/profiles/76561198082440463?time=1430031600 (April 26th)

http://backpack.tf/profiles/76561198082440463?time=1430118000 (April 27th)

http://www.tf2outpost.com/trade/25599036

60 keys seems fine

Sale 2)

sold for mg wet works + pro ks aussie smg + 3keys in sweets

http://backpack.tf/profiles/76561198058357001?time=1430895600 (May 6th)

http://backpack.tf/profiles/76561198058357001?time=1430982000 (May 7th)

40 (no overpay needed) + .9*(14.6+3)

~56 keys

Mini on SMG:

SCM sales ~35 USD

35/2.4= ~14.6 keys

Mini on wet works

Sold for 40 keys pure

http://backpack.tf/profiles/76561198015035843?time=1429340400 (April 18th)

http://backpack.tf/profiles/76561198015035843?time=1429426800 (April 19th)

Sale 3) *OUTLIER*

sold for frostbite sole mate

http://backpack.tf/profiles/76561198076005517?time=1431414000 (May 12th)

http://backpack.tf/profiles/76561198076005517?time=1431500400 (May 13th)

80*.9= 72

~72 keys

Sales: 56, 60, 72

72 seems to be an outlier, taking 56-60.

*Edit: I didn't check the last suggestion, I found the same sales as aaron though xD