4 in existence, 2 have sold recently.

Sale 1:

(See Mini#1)

The Item: http://backpack.tf/item/1239835847

The Trade: http://www.tf2outpost.com/trade/24072506 [There may be a more recent one but I couldn't find it]

Seller: http://backpack.tf/profiles/76561198119341815?time=1420561065

Buyer: http://backpack.tf/profiles/76561198066881257?time=1420589658

Sold for a duped Spellbound Nanobalaclava + 1 bud.

(2*0.9)+1 = 2.8 buds

Nanobalaclava: http://backpack.tf/item/2071411930

Earbud: http://backpack.tf/item/225320255

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Sale 2 {outlier}:

(See Mini#2 & #3)

The Item: http://backpack.tf/item/1239835847

The Trade: --- Can't find trade

Seller: http://backpack.tf/profiles/76561198066881257?time=1421192578

Buyer: http://backpack.tf/profiles/76561198022110827?time=1427173251

Sold for a Nuts n' Bolts Soldier's Stash.

1.8 buds

Stash: http://backpack.tf/item/853172913

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Sale 3:

The Item: http://backpack.tf/item/3478202120

The Trade: http://www.tf2outpost.com/trade/24666490

Seller: http://backpack.tf/profiles/76561197999019958?time=1422432000

Buyer: http://backpack.tf/profiles/76561197966756586?time=1427133863

Sold for 3 buds.

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Minis:

#1 - Duped Nanobalaclava: http://backpack.tf/item/2071411930 - Sold for 2 buds.

Seller: http://backpack.tf/profiles/76561198119341815?time=1424556077

Buyer: http://backpack.tf/profiles/76561198066881257?time=1420589658

#2 - Soldier's Stash: http://backpack.tf/item/853172913 - Sold for a Strange Specialized Killstreak Australium Black Box (See Mini#3 - Using SCM for this) + 3 keys.

Seller: http://backpack.tf/profiles/76561198066881257?time=1424073600

Buyer: http://backpack.tf/profiles/76561198002757046?time=1427059390

Black Box: http://backpack.tf/item/3031477436

1.67*0.9 = 1.5 buds

3/12 = 0.25

1.5+0.25 = 1.75 (Rounded to 1.8 buds)

Buds were 12 keys: http://backpack.tf/vote/id/54dbfe63b98d8841718b4706

#3 - Black Box: http://backpack.tf/item/3031477436

Recent sales: ($USD) $51.72 ($44.97), $58.96 ($42.57), $46.00 ($40.00) & $39.70 ($34.52): Average is $40.51.

($AfterTax)

Black Box: http://steamcommunity.com/market/listings/440/Strange%20Australium%20Black%20Box

Keys: http://steamcommunity.com/market/listings/440/Mann%20Co.%20Supply%20Crate%20Key

Keys are ~2.42 on SCM = 16.73 (Rounded to 16.7 keys)

16.7/10 = 1.67 buds

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As always, please try and keep the comments relevant, please don't make comment comprised only of "upvote" or "downvote". Counter-proof / supportive proof is always appreciated!