Resuggestion, thanks to K1ng for the info!

Sale 1:

https://backpack.tf/profiles/76561198216772865#!/compare/1564012800/1566086400

https://backpack.tf/profiles/76561198149257716#!/compare/1566000000/1566086400

Sold for 10 keys

Sale 2:

https://backpack.tf/profiles/76561198149257716#!/compare/1566432000/1566518400

https://backpack.tf/profiles/76561198045174236#!/compare/1566432000/1566518400

Bulk QS

Sale 3:

https://backpack.tf/profiles/76561198324282914#!/compare/1565913600/1566000000

https://backpack.tf/profiles/76561198337734785#!/compare/1565913600/1566000000

QS

Sale 4:

https://backpack.tf/profiles/76561198052971045#!/compare/1565913600/1566086400

https://backpack.tf/profiles/76561198876593760#!/compare/1566000000/1566086400

Sold for 12 keys

Sale 5:

https://backpack.tf/profiles/76561198876593760#!/compare/1566432000/1566518400

https://backpack.tf/profiles/76561198071167440#!/compare/1566432000/1566518400

Sold for 8 keys(?)

Sale 6:

https://backpack.tf/profiles/76561198071167440#!/compare/1566691200/1566777600

https://backpack.tf/profiles/76561198143581382#!/compare/1566691200/1566777600

Sold for 10 keys

Sale 7:

https://backpack.tf/profiles/76561198143581382#!/compare/1567209600/1567382400

https://backpack.tf/profiles/76561198204215081#!/compare/1567296000/1567382400

Sold for Aces Crasher

Crasher Mini:

https://backpack.tf/suggestion/5d8e68dcd38172551251b3a1

Suggestion for 13 keys

Sale 8:

https://backpack.tf/profiles/76561198204215081#!/compare/1567468800/1567555200

https://backpack.tf/profiles/76561198240516044#!/compare/1567468800/1567555200

Sold with negligible sweets for DBD Shutter

use there

Sale 9:

https://marketplace.tf/items/tf2/30318;5;u57

$33 / $1.85 = 17.84 keys

Sale 10:

https://backpack.tf/profiles/76561198165604761#!/compare/1509321600/1568592000

https://backpack.tf/profiles/76561198453530349#!/compare/1568678400/1568764800

Sale 11:

https://backpack.tf/profiles/76561198240516044#!/compare/1569196800/1569369600

https://backpack.tf/profiles/76561198118180831#!/compare/1569283200/1569369600

Sold for ~9.5 keys

Total sales @:

8, 9.5, 10, 10, 12, 13, 17.84

buyers up to 7 keys,

seller for ~12 keys has been dropping,

seller for 10 keys dropped recently,

https://bot.tf/stats/listings/YDL9DWZX <-- selling for 12 keys here,

calling 8 low,

17 high,

K1ng's Part:

Low-end should be rounded up to 10. Aces Crasher is a mess, so better not to use that here.

10-12 should be okay.