https://marketplace.tf/items/tf2/15057;15;u704;w3;pk57

August 30, 2019 - $99.99 = 55 keys

https://marketplace.tf/items/tf2/15057;15;u704;w3;pk57;kt-2;festive

July 11, 2019 - $119.99 = 65 keys

https://marketplace.tf/items/tf2/15057;15;u704;w3;pk57;kt-3

September 11, 2019 - $109.99 = 61 keys

https://marketplace.tf/items/tf2/15057;15;u704;w3;pk57;festive

July 21, 2019 - $123.99 = 69 keys

nice

https://marketplace.tf/items/tf2/15057;15;u704;w3;pk57;kt-3;festive

August 11, 2019 - $140.00 = 77 keys

https://backpack.tf/profiles/76561198035780190#!/compare/1563321600/1563494400

https://backpack.tf/profiles/76561198418740133#!/compare/1563408000/1563494400

63 keys

https://backpack.tf/profiles/76561198035780190#!/compare/1562716800/1562803200

https://backpack.tf/profiles/76561198030343929#!/compare/1562630400/1562716800

Untraceable, most likely went through marketplace

https://backpack.tf/profiles/76561197968339983#!/compare/1562284800/1565395200

https://backpack.tf/profiles/76561198010059325#!/compare/1562371200/1562457600

Untraceable

https://backpack.tf/profiles/76561198151561701#!/compare/1566259200/1566345600

https://backpack.tf/profiles/76561198210700703#!/compare/1566259200/1566345600

Starstorm Spook Specs (43 keys) + 19 keys = 62 keys

https://backpack.tf/profiles/76561197994697258#!/compare/1564704000/1564790400

https://backpack.tf/profiles/76561198210700703#!/compare/1564704000/1564790400

Strange Unique Rocket Launcher, a high outlier

https://backpack.tf/suggestion/5d6eea45678072100a2fcc37

https://backpack.tf/profiles/76561197994697258#!/compare/1563321600/1563408000

https://backpack.tf/profiles/76561198083831074#!/compare/1563408000/1563580800

Already used here

Here's all of the item histories that have moved recently. Most of them, hopefully it's all of them.

https://backpack.tf/item/5986296247 https://backpack.tf/item/3974625798 https://backpack.tf/item/4073344342

https://backpack.tf/item/3933150566 https://backpack.tf/item/6019145153 https://backpack.tf/item/6140133449

Sales:

55, 61, 62, 63, 65, 69, 77

Sellers:

https://imgur.com/a/RR3UneJ

https://backpack.tf/classifieds?item=Rocket+Launcher&tradable=1&craftable=1&texture_name=Aqua+Marine&wear=Field-Tested&particle=704&australium=-1

60 keys - 1 day

65 keys - 2 days

75 keys - 2 months

Going with 60-70 keys, excluding 55 and 77 as low and high outliers respectively.