Genuine Cube

Couple more sales:
https://backpack.tf/item/1568073279 - your item history
Sale 1
https://backpack.tf/profiles/76561197975240268#!/compare/1613520000/1614729600
https://backpack.tf/profiles/76561198109986831#!/compare/1614902400/1615075200
Untrace

Item 2
https://backpack.tf/item/4209675811
Sale 2
https://backpack.tf/profiles/76561198036855813#!/compare/1614211200/1614643200
https://backpack.tf/profiles/76561198063485354#!/compare/1614124800/1616284800
Untrace

Item 3
https://backpack.tf/item/2261495297
Sale 3
https://backpack.tf/profiles/76561198115993090#!/compare/1590796800/1614729600
https://backpack.tf/profiles/76561198453530349#!/compare/1614643200/1614729600
Untrace

Sale 4
https://backpack.tf/profiles/76561198453530349#!/compare/1615075200/1615161600
https://backpack.tf/profiles/76561198076639682#!/compare/1615075200/1615161600
1 key matches
https://gladiator.tf/listings/604562efc4ed05fa1088af3f - buyout was 30 keys

Item 4 - duped
https://backpack.tf/item/1430891957
Sale 5
https://backpack.tf/profiles/76561198353389785#!/compare/1614988800/1615075200
https://backpack.tf/profiles/76561198342161127#!/compare/1615075200/1615161600
Untrace

Marketplace sales
https://marketplace.tf/items/tf2/864;1
Feb 19th - $40 / $2.12 = 18.87 keys

SCM sales
https://steamcommunity.com/market/listings/440/Genuine%20Friends%20Forever%20Companion%20Square%20Badge
Feb 22nd - $71.45 / $2.39 = 29.90 keys
Mar 11th - $81.47 / $2.52 = 32.33 keys
Mar 24th - $48.79 / $2.49 = 19.59 keys
Apr 29th - $50.66 / $2.40 = 21.10 keys

[u]Sales[/u]
18.9, 30, 32, 19.6, 21.1

Including your purchase at 35 keys, I'm much more inclined to go 30 - 35 keys here given sellers at 35 keys and buyers at 25 keys