Resuggestion, thanks to K1ng for the info!

Sale 1:

https://backpack.tf/profiles/76561198133605006#!/compare/1567209600/1568419200

https://backpack.tf/profiles/76561198194775141#!/compare/1569542400/1569628800

Sold with 7 keys for Neutron France(39)

Total is 32 keys

https://bot.tf/stats/listings/MQ9QVEO0

B/O of 37 keys

Sale 2:

https://backpack.tf/profiles/76561198194775141#!/compare/1569628800/1569715200

https://backpack.tf/profiles/76561198097285216#!/compare/1569628800/1569715200

Sold for CTFL Stahlhelm + 17 keys

Sathl Mini:

https://backpack.tf/suggestion/5dab5409d3817261c869d5c1

Suggestion for 21.5 keys

Total is 38.5 keys

https://bot.tf/stats/listings/Y9GX5V7W

B/O of 40 keys

Sale 3:

https://backpack.tf/profiles/76561198280357510#!/compare/1563667200/1563753600

https://backpack.tf/profiles/76561198087099341#!/compare/1563580800/1563753600

Bulky

Sale 4:

https://backpack.tf/profiles/76561198087099341#!/compare/1564358400/1564531200

https://backpack.tf/profiles/76561198134512931#!/compare/1564272000/1564531200

Bulky

Sale 5:

https://backpack.tf/profiles/76561198134512931#!/compare/1568246400/1568332800

https://backpack.tf/profiles/76561198434669555#!/compare/1568246400/1568332800

Sold for 34 keys

Sale 6:

https://backpack.tf/profiles/76561198434669555#!/compare/1568419200/1568678400

https://backpack.tf/profiles/76561198076804761#!/compare/1568419200/1568505600

https://backpack.tf/profiles/76561198434669555#!/compare/1568332800/1568419200

transfers

Total sales @:

32, 34, 38.5 keys

buyers up to 31 keys,

new seller for 38 keys,

gonna call 32 low,

K1ng's Part:

Buyers at 31 are now gone. Other sales:

31 keys

https://backpack.tf/profiles/76561198097285216#!/compare/1572480000/1572652800

https://backpack.tf/profiles/76561198171962935#!/compare/1572566400/1572652800

31 keys (likely via buy order)

https://backpack.tf/profiles/76561198171962935#!/compare/1574035200/1574121600

https://backpack.tf/profiles/76561198335791307#!/compare/1573948800/1574035200

So 31-39 should work.