Cauldron Bubbles Crone's Dome (475)
https://backpack.tf/stats/Unusual/Crone's%20Dome/Tradable/Craftable/39

Sale 1)
https://backpack.tf/profiles/76561198119149660#!/compare/1560643200/1560729600
https://backpack.tf/profiles/76561198803829026#!/compare/1560556800/1560729600 - Sold for a Duped Vintage Community Sparkle Professional Killstreak Lugermorph (410) + A Strange Current Event Scattergun (Factory New) (65) = 475 Keys
No Buyout

[i]Mini for Scatter:[/i]
https://steamcommunity.com/market/listings/440/Strange%20Current%20Event%20Scattergun%20%28Factory%20New%29
Sale at £124.49 / £1.91 = 65 Keys

[i]Mini for Luger:[/i]
https://backpack.tf/profiles/76561198218497692#!/compare/1564704000/1564790400 - No Mini on Sticky, supports tho
https://backpack.tf/profiles/76561197994783413#!/compare/1564185600/1564272000 - Seems high
https://backpack.tf/profiles/76561198116779194#!/compare/1565913600/1566000000 - Untrace
https://backpack.tf/profiles/76561198168863803#!/compare/1566000000/1566086400 - Sold for a Nebula A Head Full of Hot Air (56) + 332 Keys = 388 Keys
https://marketplace.tf/items/tf2/160;3;u4;kt-3 - Oldish sale (valid for a mini) $777.78 / $1.8 = 432 Keys
https://backpack.tf/profiles/76561198042012776#!/compare/1562803200/1562889600 - Sold for 400 Keys
Taking 410 as a Mini from the Mid-Point of 388 - 432

Sale 2)
https://backpack.tf/profiles/76561197971485686#!/compare/1559692800/1559952000
https://backpack.tf/profiles/76561198119149660#!/compare/1559865600/1559952000 - Sold via Mp.tf, MISTA Is known for mp.tf sales
https://marketplace.tf/items/tf2/920;5;u39 - $575 / $1.80 = 319.44 Keys = 319 Keys
No Buyout

Summary:
475

The 4 Month unsold is for a duped one but it supports a drop here - https://gyazo.com/a2fbac7b65c64466d57222d9efbe5462