Sale 1:

https://backpack.tf/profiles/76561198125295112#!/compare/1585526400/1585612800

https://backpack.tf/profiles/76561198155110999#!/compare/1585440000/1585526400

QS for ~20 keys

sale 2:

https://backpack.tf/profiles/76561198212407403#!/compare/1584576000/1584662400

https://backpack.tf/profiles/76561198334946156#!/compare/1584576000/1584662400

sold with 3 keys for Vivid Nickel

use there

sale 3:

https://backpack.tf/profiles/76561198402901200#!/compare/1587686400/1587772800

https://backpack.tf/profiles/76561198156255538#!/compare/1587600000/1587686400

Bulky

sale 4:

https://marketplace.tf/items/tf2/15055;15;u701;w3;pk55;kt-2

$45.99 / $1.69 = 27.21 keys

Sale 5:

https://marketplace.tf/items/tf2/15055;15;u701;w3;pk55

48 / 1.9 = 25.26 keys

Sale 6:

https://marketplace.tf/items/tf2/15055;15;u701;w3;pk55;festive

$40 / $1.69 = 23.67 keys

37 / 1.89 = 19.57 keys

Total sales @:

20, 20, 24, 25, 27 keys

buyers up to ~20 keys

2 month unsold for 24 keys,

https://backpack.tf/classifieds?item=Brick%20House%20|%20Minigun%20(Field-Tested)&quality=15&tradable=1&craftable=1&australium=-1&particle=701&killstreak_tier=0

taking 24 - 25 keys