Resuggesting from: https://backpack.tf/suggestion/5aba476ecf6c75678b608dd3#comment-5abc461844325a472c54a3c0

sale 1:

105 keys

https://web.archive.org/web/20180207213849/https://marketplace.tf/items/5021;6/Mann%20Co.%20Supply%20Crate%20Key

keys at the time were $1.90

$200/1.90 = 105 keys

https://marketplace.tf/items/30653;5;u96/Voltaic%20Hat%20Protector%20Sucker%20Slug

sale 2:

Obtained together so ¯\_(ツ)_/¯

https://backpack.tf/profiles/76561198066195760#!/compare/1516752000/1516838400

sale 3:

113 keys, rounding to 115 for a better range

Burning Flames Virtual Reality Headset(89) + Strange Steaming Executioner(24)

https://backpack.tf/profiles/76561198028307864#!/compare/1517097600/1517184000

https://backpack.tf/profiles/76561198066195760#!/compare/1517097600/1517184000

Virtual Reality Headset mini:

120-5=115 115-26= 89

Sold with Vivid Hive Minder(26) for Cloudy Moon Sergeant's Drill Hat(120) and 5 keys

https://backpack.tf/profiles/76561198106233311#!/compare/1520899200/1520985600

https://backpack.tf/profiles/76561198161635287#!/compare/1520726400/1520985600

Hive Minder mini:

Sold for 26 pure

https://backpack.tf/profiles/76561198053717045#!/compare/1520553600/1520640000

https://backpack.tf/profiles/76561198161635287#!/compare/1520553600/1520640000

Virtual Reality Headset unsold at 160 for 2 months:

https://i.imgur.com/OmvRD8U.png

Virtual Reality Headset unsold at $300 (150 keys) for 3 months:

https://marketplace.tf/items/628;5;u13/Burning%20Flames%20Virtual%20Reality%20Headset

Taking 89

Slug unsold at $419 = 210 keys

https://marketplace.tf/items/30653;5;u96/Voltaic%20Hat%20Protector%20Sucker%20Slug

https://backpack.tf/item/5728215712

Final 105-115