https://marketplace.tf/items/tf2/106;5;u16 - Sold for $25 (14 Keys). Pretty sure this was to a buy order.

https://backpack.tf/item/961848483 - $25 sale history

https://marketplace.tf/items/tf2/106;5;u16;kt-2 - Sold for $55 (high)

https://backpack.tf/item/280867364 - $55 sale history

https://backpack.tf/profiles/76561197986864096#!/compare/1564963200/1565222400 - Sold for 19 Keys

https://backpack.tf/profiles/76561198069800407#!/compare/1570752000/1570838400 - Sold for 16 Keys

https://backpack.tf/profiles/76561198119381698#!/compare/1566000000/1566518400 - Sold for 12 Keys

https://backpack.tf/profiles/76561198137163870#!/compare/1566432000/1566518400 - Quicksold for 9 Keys?

https://backpack.tf/profiles/76561198290053747#!/compare/1566518400/1566691200 - Sold + 6 Keys for a Purple Energy Polar Puffy Cap (26 Keys)

https://backpack.tf/profiles/76561198090750997#!/compare/1566604800/1566691200 - Buyer's side of the Puffy sale

https://bot.tf/stats/listings/MXQPZQQ1 - Puffy sale capped by the buyout of 18 Keys

https://backpack.tf/profiles/76561198090750997#!/compare/1566604800/1566691200 - Sold for a Cloud 9 Bomber's Bucket Hat

https://backpack.tf/profiles/76561198146883929#!/compare/1566604800/1566691200 - Sold for a Disco Beat Down Desert Marauder

https://backpack.tf/profiles/76561198116105833#!/compare/1566777600/1566950400 - Sold for a Strange FN Pro KS Star Crossed Scatter + 2 Keys

https://backpack.tf/profiles/76561198314776045#!/compare/1566864000/1566950400 - Quicksold for 13 Keys

https://backpack.tf/profiles/76561198314776045#!/compare/1567036800/1567123200 - Sold for 16 Keys + 22 Refined

Since I think 14 was to a buy order, 15 - 19 should work. This'll put your Omniscient Orb Hellmet suggestion at 26 - 27.