Boink

https://backpack.tf/item/3124071339

Sale 1) Sold for a HG Bonk Boy (121 Keys) + SF Larrikin (45.5 Keys) + HP Jr Scout Shako (40 Keys) + Pro KS Aussie Sniper (~36 Keys) + Double-Spelled Drummer

https://backpack.tf/profiles/76561198151835897#!/compare/1559520000/1559779200

Was told to take 0 for the price of the Drummer since there's no Mini -> https://imgur.com/a/AInKw34

121 + 45.5 + 40 + 36 = 242.5, which I'll round up to 245 Keys

Bonk Mini

https://backpack.tf/suggestion/5d5f55ab6780722d44263e23 - 121 Keys

Robin Mini

https://backpack.tf/suggestion/5d61ec05d3817213b93301ce - 45.5 Keys

Shako Mini

https://backpack.tf/suggestion/5d5f4946d381723db04c4946 - 40 Keys

Sale 2) Sold + Field-Tested Energy Orb Night Terror Scattergun for 200 Keys

https://gyazo.com/32bfac9798228e12ec640dabab62d54a - Thanks Reflex

https://backpack.tf/item/3930707560 - Scattergun

Reflex listed it on Marketplace before his backpack was scanned.

Sale 3) Sold for $368.99 when Keys were ~$1.73 each

https://mannco.store/item/13866/

https://mannco.store/item/1

368.99 / 1.73 = 213.29, which rounds to 213 Keys

https://imgur.com/a/NTv06YB - Capped by the Buyout of 200 Keys