Themed because fire and solder.

https://backpack.tf/item/4694085628

Sale 1) I don't know

https://backpack.tf/profiles/76561198045694677#!/compare/1524614400/1524700800

https://backpack.tf/profiles/76561198021572167#!/compare/1524441600/1525046400

https://backpack.tf/item/2479710402

Sale 2) Bulk Sale

https://backpack.tf/profiles/76561198043991016#!/compare/1522540800/1522627200

Sale 3) Bulk Sale

https://backpack.tf/profiles/76561198070474543#!/compare/1522627200/1522713600

https://backpack.tf/item/3015109613

Sale 4) Sold + 13 Keys for a Sunbeams Samur-Eye (165 Keys)

https://backpack.tf/profiles/76561198030462768#!/compare/1523145600/1523664000

165 - 13 = 152, which I'll round to 150 Keys

Samur-Eye Mini

https://backpack.tf/suggestion/5b35b5afcf6c757aaa6c09eb - 165 Keys

Sale 5) Sold + 30 Keys + Pro KS Aussie FJ (~12 Keys) + Strange VHP HFoHA (10 Keys) + P. Fetti Elf Esteem (8 Keys) + MS Bronco (7 Keys) for a C. Heart Prehistoric (275 Keys)

https://backpack.tf/profiles/76561198090560650#!/compare/1523318400/1523664000

https://backpack.tf/profiles/76561198037631433#!/compare/1523577600/1523664000

275 - 30 - 12 - 10 - 8 - 7 = 208, which I'll round to 210 Keys

Head Full of Hot Air Mini

https://backpack.tf/profiles/76561198037631433#!/compare/1523577600/1523664000 - Only sale I can figure out is a quicksale for 10 Keys

https://backpack.tf/profiles/76561198067788569#!/compare/1523664000/1523923200 - Buyer's side

https://backpack.tf/profiles/76561197960788095#!/compare/1526515200/1526601600 - Bulk for a Screaming Tiger High Five

https://backpack.tf/profiles/76561198095236132#!/compare/1526428800/1526601600 - Buyer's side

https://backpack.tf/profiles/76561198095236132#!/compare/1528329600/1528502400 - ?

https://backpack.tf/profiles/76561198044026115#!/compare/1528502400/1528588800 - Buyer's side

Elf Esteem Mini

https://backpack.tf/profiles/76561198142488407#!/compare/1529020800/1529193600 - Sold for 8 Keys

https://imgur.com/a/aCoNrUq - Sales from 7.5 - 8 Keys

https://backpack.tf/profiles/76561198356155747#!/compare/1527292800/1527465600 - Quicksold for 8 Keys

https://backpack.tf/profiles/76561198424066729#!/compare/1527033600/1527465600 - Buyer's side

Sale 6) Sold for a Heart Modest Metal (62 Keys) + Mallard Dread Hiding (56.5 Keys) + Sunbeams Polar Puffy + Terror Tyrolean (22 Keys) + Planets Belt

https://backpack.tf/profiles/76561198037631433#!/compare/1523664000/1523750400

Fits in the range.

Modest Mini

https://backpack.tf/suggestion/5b29771a44325a6f1e0ebc62 - Taking 62 Keys from here

Dread Mini

https://backpack.tf/suggestion/5b35c25fcf6c75102c39a62b - 56.5 Keys

Puffy Mini

https://imgur.com/a/xrh2Jrq - 1 Month Unsold at 46 Keys

Sale 7) Sold for 140 Keys + Purple Energy Desert Marauder (54.5 Keys)

https://backpack.tf/profiles/76561198114402400#!/compare/1528416000/1528502400

140 + 54.5 = 194.5, which rounds to 195 Keys

Desert Mini

https://backpack.tf/suggestion/5b35ca94cf6c750290704b74 - 54.5 Keys

Calling 150 low.