https://backpack.tf/profiles/76561198056793885#!/compare/1613001600/1613088000 ~ 4945 Keys (rounding to 4900)

https://backpack.tf/item/2047232897 ~ Item

Sale) Sold for a Purple Energy Polar Pullover (2700 Keys) + Harvest Moon Aztec Aggressor + Stormy 13th Valley Forge + Chiroptera Venenata Belgian Detective + Flaming Lantern Das Hazmattenhatten + Accursed Conga + It's A Secret To Everybody Ye Olde Baker Boy (1616 Keys together) + Sunbeams Pyromancer's (535 Keys) + 94 Keys

2700 + 1616 + 535 + 94 = 4945, which can be rounded down to 4900 Keys to account for the Scorching Flames Exquisite Rack mini being a little high

Aztec, Valley, Belgian, Hazmat, Conga, and Baker Mini

https://backpack.tf/profiles/76561198056793885#!/compare/1613088000/1613174400 ~ Sold + 94 Keys for a Scorching Flames Exquisite Rack (1035 Keys) + Duped Cloudy Moon Villain's Veil (675 Keys)

1035 + 675 - 94 = 1616 Keys

Note ~ A couple minis are 4+ months old but no more than 5+ months old as there is nothing else to use and they would have all been valid if this suggestion was made earlier so this should be ok for this circumstance as minis for pricing the Hellfire Exquisite Rack as opposed to full suggestions on their own.

Scorching Flames Exquisite Rack Mini ~ 1035 Keys

https://backpack.tf/item/207170201 ~ Item

Sale 1) Sold for 770 Keys + Vivid Plasma Soldier's Stash (300 Keys)

https://backpack.tf/profiles/76561198175905570#!/compare/1607472000/1607558400

https://gyazo.com/d51556b38b8bb1dd0198c78c51357088

770 + 300 = 1070 Keys

Vivid Plasma Soldier's Stash Mini

https://backpack.tf/profiles/76561198044925142#!/compare/1610064000/1610150400 ~ Sold for a Searing Plasma Pyromancer's Mask (225 Keys) + Green Black Hole Little Buddy (61.5 Keys) + Miami Nights Ol' Geezer (12 Keys)

225 + 61.5 + 12 = 298.5, which rounds to 300 Keys

Searing Plasma Pyromancer's Mask Mini

https://backpack.tf/profiles/76561197994697258#!/compare/1617580800/1617667200 ~ Sold for a Steaming Exquisite Rack (105 Keys) + Circling Peace Sign Le Party Phantom (97 Keys) + Purple Confetti Conjurer's Cowl (13 Keys) + 10 Keys

105 + 97 + 13 + 10 = 225 Keys

Steaming Rack Mini

https://backpack.tf/suggestion/608db8acb37974172025bc9d ~ 105 Keys

Circling Peace Sign Le Party Phantom Mini

https://backpack.tf/profiles/76561198328282971#!/compare/1617235200/1617321600 ~ Sold for a Prismatica Breach and Bomb (87.5 Keys) + 16 Keys

https://imgur.com/a/M4O162J ~ Sellers between 90 and 105 Keys

https://backpack.tf/item/207199569

https://backpack.tf/item/234735195

https://backpack.tf/item/968976855

90 to 104 Keys will work for the Phantom's price.

Breach and Bomb Mini

https://backpack.tf/suggestion/608dbdf0d3dd542dba28da50 ~ 87.5 Keys

Purple Confetti Conjurer's Cowl Mini

https://backpack.tf/profiles/76561198073788829#!/compare/1613174400/1613865600 ~ Sold for 13 Keys + 9.11 Refined

Rounds to 13 Keys

Green Black Hole Little Buddy Mini

https://backpack.tf/suggestion/608db6dc2db77a79cf3b9d20 ~ 61.5 Keys

Miami Nights Ol' Geezer Mini

https://backpack.tf/profiles/76561199119484218#!/compare/1610323200/1610409600 ~ Sold for 12 Keys

https://backpack.tf/profiles/76561197961094927#!/compare/1610064000/1610150400 ~ Sold for 18 Keys

https://gladiator.tf/listings/5ff8c66835e972ca84ef1253 ~ 18 Keys is too high since there was a seller at the same time at 14 Keys

Sale 2) Bulk sale

https://backpack.tf/profiles/76561198175905570#!/compare/1609891200/1609977600

https://backpack.tf/profiles/76561198139171368#!/compare/1609804800/1609891200

Sale 3) Bulk sale

https://backpack.tf/profiles/76561198139171368#!/compare/1613088000/1613174400

https://backpack.tf/profiles/76561198056793885#!/compare/1613088000/1613174400

Sale 4) Bulk sale

https://backpack.tf/profiles/76561198056793885#!/compare/1613347200/1613606400

https://backpack.tf/profiles/76561198088878793#!/compare/1613520000/1613606400

https://imgur.com/a/U41J6uD ~ Sellers at 1000 Keys

https://backpack.tf/item/430997139

https://backpack.tf/item/207170201

https://backpack.tf/item/659738714

1000 to 1070 will work for the Rack's price.

Duped Cloudy Moon Villain's Veil Mini ~ 675 Keys

https://backpack.tf/item/561503610 ~ Item

Sale 1) Sold for a Harvest Moon Fancy Fedora + Burning Flames Surgeon's Stahlhelm + Cool Specialized Killstreak Sand Cannon Rocket Launcher (Well-Worn) + Plum Prankster Punk's Pomp

https://backpack.tf/profiles/76561198838788284#!/compare/1612310400/1612396800

https://backpack.tf/profiles/76561198218497692#!/compare/1612310400/1612396800

Multiple items don't have Minis, so this sale can be excluded.

Sale 2) Sold + Laugh-O-Lantern Rotation Sensation (135 Keys) for a Purple Energy Aztec Warrior (350 Keys) + Steaming Antlers (297.5 Keys) + Frozen Icefall Winter Wrap Up + Strange Galactic Gateway Hephaistos' Handcraft (215.5 Keys together)

https://backpack.tf/profiles/76561198218497692#!/compare/1612310400/1612396800

https://backpack.tf/profiles/76561198139171368#!/compare/1612310400/1612396800

350 + 297.5 + 215.5 - 135 = 728, which can be rounded to 725 Keys.

Laugh-O-Lantern Rotation Sensation Mini

https://backpack.tf/suggestion/6085953d43d6c70c79249619 ~ 135 Keys

Purple Energy Aztec Warrior Mini

https://backpack.tf/suggestion/6084b20fb158dd71a11d3547 ~ 350 Keys

Strange Galactic Gateway Hephaistos' Handcraft Mini

https://backpack.tf/profiles/76561198032481426#!/compare/1612310400/1612483200 ~ Sold + 15 Keys + Smoking Cloud Crasher (10.5 Keys) for a Cloudy Moon Modest Pile of Hat (241 Keys)

241 - 15 - 10.5 = 215.5 Keys

Smoking Cloud Crasher Mini

https://backpack.tf/profiles/76561198032481426#!/compare/1612656000/1612915200 ~ Sold for 7 Keys + Collector's Festive FaN Set (3 Keys)

https://steamcommunity.com/market/listings/440/Collector%27s%20Festive%20Force-A-Nature%20Chemistry%20Set ~ Set goes for 3 Keys

https://cdn.discordapp.com/attachments/433086365144580107/835274924997607444/63db1cf38a2dbee6648b1aebcd39a0c8.png ~ Sold for 11 Keys

Cloudy Moon Modest Pile of Hat Mini

https://backpack.tf/profiles/76561198027354784#!/compare/1611014400/1611100800 ~ Sold for 145 Keys + Cloudy Moon Scotch Bonnet (96 Keys)

https://backpack.tf/profiles/76561198218497692#!/compare/1612569600/1612656000 ~ Bulk sale

https://backpack.tf/profiles/76561198140316312#!/compare/1613433600/1613520000 ~ Sold for 160 Keys + Vivid Plasma Killer Exclusive + Strange Festivized Australium Grenade Launcher

https://backpack.tf/profiles/76561198049469629#!/compare/1613952000/1614038400 ~ Sold for a Scorching Flames Brown Bomber (137.5 Keys) + Purple Energy Honcho's Headgear (58.5 Keys)

The KE sale is 230 Keys minimum and was dumped for 196 Keys, so both of those can be excluded.

241 works for the Modest's price as a Mini, even though it's 3.5 months old.

Cloudy Moon Scotch Bonnet Mini

https://backpack.tf/suggestion/6061183dac05d358d2263e53 ~ The comments would make this 96 Keys

Purple Energy Honcho's Headgear Mini

https://backpack.tf/suggestion/6085c85d3871385b007a1fda ~ 58.5 Keys

Sale 3) Bulk sale

https://backpack.tf/profiles/76561198139171368#!/compare/1613088000/1613174400

https://backpack.tf/profiles/76561198056793885#!/compare/1613088000/1613174400

Sale 4) Sold + Duped Circling Peace Sign Bonk Boy for a Duped Scorching Flames Exquisite Rack (620 Keys)

https://backpack.tf/profiles/76561198105071091#!/compare/1613433600/1613606400

Low outlier.

Duped Scorching Flames Exquisite Rack Mini

https://gyazo.com/771e42328f85b87d68148109114b8b41 ~ 620 Keys

Sale 5) Sold for a bunch of items

https://backpack.tf/profiles/76561198105071091#!/compare/1613865600/1613952000

https://gyazo.com/490b43d9d95da16741e60fca7bb5c670

Multiple items don't have Minis, so this sale can be excluded.

Sale 6) Sold for an Arcana Company Man (625 Keys)

https://backpack.tf/profiles/76561198326511775#!/compare/1619136000/1619222400

Arcana Company Man Mini

https://backpack.tf/suggestion/608dac0d238f6921fb01f9cf ~ 625 Keys