Re-suggestion, thanks to Joxu for the additional sale and K1NG for the info!

Sale 1:

https://backpack.tf/profiles/76561198035882130#!/compare/1525824000/1526083200

https://steamcommunity.com/market/listings/440/Unusual%20Lightning%20Rod%20Shotgun%20%28Battle%20Scarred%29

Sold for 141.85 CAD

Keys at 3.20 CAD

Total is 44.33 keys

Sale 2:

https://backpack.tf/profiles/76561198002757046#!/compare/1524355200/1524441600

https://backpack.tf/profiles/76561198409022488#!/compare/1524441600/1524614400

Sold for 28 keys

Sale 3:

https://backpack.tf/profiles/76561198409022488#!/compare/1524873600/1524960000

https://backpack.tf/profiles/76561198436732041#!/compare/1524873600/1524960000

Sold for FT Isotope Flower Power Shotgun

Shotgun mini:

https://backpack.tf/profiles/76561198002757046#!/compare/1523059200/1523145600

https://backpack.tf/profiles/76561198069410757#!/compare/1522972800/1523577600

Sold for 18 keys

Only sale I can trace.

https://i.imgur.com/LAZjbmI.jpg

Buyer up to 25.

New bulk sale:

https://backpack.tf/profiles/76561198331636801#!/compare/1531008000/1531180800

https://backpack.tf/profiles/76561198157176919#!/compare/1531094400/1531267200

K1NG's Part:

Well, nothing is countering the sale at 28 and turns out that 28-44 would be a refresh. I would go with 28-44 here.

Taking 28 - 44 keys.