Re-suggestion, thanks to Mindacos for the info!

Sale 1:

https://backpack.tf/profiles/76561197993834789#!/compare/1527206400/1527292800

https://backpack.tf/profiles/76561198179707937#!/compare/1527206400/1527292800

Sold with 5 keys for OF Pencil Pusher(25.5)

Total is 20.5 keys.

Sale 2:

https://backpack.tf/profiles/76561198179707937#!/compare/1527724800/1527811200

https://backpack.tf/profiles/76561198121830870#!/compare/1527724800/1527811200

Sold for 17 keys

Sale 3:

https://backpack.tf/profiles/76561198047340195#!/compare/1526515200/1528070400

https://backpack.tf/profiles/76561198089754977#!/compare/1527897600/1527984000

https://steamcommunity.com/market/listings/440/Unusual%20Forest%20Fire%20Flame%20Thrower%20%28Field-Tested%29

Sold on SCM for 30.89 CAD

QS, not using.

Sale 4:

https://backpack.tf/item/6388869008

https://backpack.tf/profiles/76561198345453690#!/compare/1524700800/1525996800

MP Sale, cannot trace.

Sale 5:

https://backpack.tf/profiles/76561198067775866#!/compare/1524787200/1524873600

https://backpack.tf/profiles/76561198209951153#!/compare/1524096000/1524787200

Sold with a key for ST Victory Lap

Lap Mini:

https://marketplace.tf/items/1172;5;u3006

Lots of sales for ~33 keys.

Taking 32 keys.

Sale 6:

https://backpack.tf/profiles/76561198209951153#!/compare/1524873600/1525219200

https://backpack.tf/profiles/76561198021055079#!/compare/1525132800/1525219200

Sold for Aussie Pro KS Tomislav(17.25)

Total sales @:

17, 17.25, 20.5, 32

https://backpack.tf/classifieds?item=Flame+Thrower&quality=15&tradable=1&craftable=1&australium=-1&particle=701

Sellers down to 23 keys

Buyers up to 17 keys.

Mindacos' Part:

Another sale:

Sold for 23 Keys

https://backpack.tf/profiles/76561198121830870#!/compare/1529798400/1529884800

21-23 should be fine for this, resuggest at that.