Many thanks to shufflespy for all the help

Sale 1:

https://marketplace.tf/items/tf2/671;5;u18

$66.99 / $1.76 = 38.06 keys

Sale 2:

b/o 25 keys: https://imgur.com/a/VGM0Mv7

KaW KE(30)

https://backpack.tf/profiles/76561198208342268#!/compare/1585612800/1585699200

https://backpack.tf/profiles/76561198003182128#!/compare/1585440000/1585785600

Sale 3:

bulk

https://backpack.tf/profiles/76561198003182128#!/compare/1585785600/1585958400

https://backpack.tf/profiles/76561198160942053#!/compare/1585872000/1586044800

Sale 4:

untrace

https://backpack.tf/profiles/76561198002757046#!/compare/1580428800/1580515200

https://backpack.tf/profiles/76561198055156807#!/compare/1526774400/1580515200

Sale 5:

C9 cotton(26 keys)

https://backpack.tf/profiles/76561198045025971#!/compare/1579219200/1579564800

https://backpack.tf/profiles/76561198292162893#!/compare/1579478400/1579564800

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cotton mini:

https://marketplace.tf/items/tf2/30175;5;u58

$45.95 / $1.78 = 25.81 keys

$49.95 / $1.67 = 29.91 keys

even taking buyers this caps at b/o

b/o 22 keys: https://imgur.com/a/xksrX6w

DBD whoopee + KaW snowcapped + 4 keys

https://backpack.tf/profiles/76561198090614429#!/compare/1584576000/1584662400

https://backpack.tf/profiles/76561198806550252#!/compare/1584576000/1584662400

------------------------------------------------------------------------------

just gambles - https://backpack.tf/item/8504904319

Sale 6:

untrace

https://backpack.tf/profiles/76561198006544512#!/compare/1581292800/1581379200

https://backpack.tf/profiles/76561198121386755#!/compare/1581292800/1581379200

Sale 7:

untrace

https://backpack.tf/profiles/76561198094230147#!/compare/1581724800/1581811200

https://backpack.tf/profiles/76561198161953994#!/compare/1582070400/1582243200

Sale 8:

untrace

https://backpack.tf/profiles/76561198161953994#!/compare/1582761600/1583107200

https://backpack.tf/profiles/76561198337734785#!/compare/1582675200/1582761600

Sale 9:

21 keys + 29 ref

https://backpack.tf/profiles/76561198337734785#!/compare/1582761600/1582848000

https://backpack.tf/profiles/76561198295506584#!/compare/1582761600/1582848000

Sale 10:

21 keys

https://backpack.tf/profiles/76561198295506584#!/compare/1583107200/1583193600

https://backpack.tf/profiles/76561198125200023#!/compare/1583107200/1583193600

Sale 11:

19 keys

https://backpack.tf/profiles/76561198125200023#!/compare/1583193600/1583366400

https://backpack.tf/profiles/76561198154023527#!/compare/1583366400/1583452800

Sale 12:

30 keys b/o: https://imgur.com/a/1uGWUuf

vivid tundra top(33)

https://backpack.tf/profiles/76561198154023527#!/compare/1583366400/1583452800

https://backpack.tf/profiles/76561198059316053#!/compare/1582502400/1583452800

tundra: https://backpack.tf/suggestion/5e96100c6a32cb4ab2285a13

Sale 13:

21 keys

https://backpack.tf/profiles/76561198058315042#!/compare/1581724800/1583280000

https://backpack.tf/profiles/76561198034755171#!/compare/1582070400/1582156800

Sale 14:

better used on chullo

sold with ~15 keys of sweets for Miami Nights Chullo + 1 key

https://backpack.tf/profiles/76561198368641361#!/compare/1585440000/1585785600

https://backpack.tf/profiles/76561197994697258#!/compare/1585699200/1585785600

Sale 15:

20 keys

credits to shuffle spy

15 keys + ~5 keys sweets

https://backpack.tf/profiles/76561198426094322#!/compare/1582502400/1582588800

https://backpack.tf/profiles/76561198084219943#!/compare/1582502400/1582588800

spelled item + RL sold for 5 keys here:

https://backpack.tf/profiles/76561198244604462#!/compare/1582588800/1582675200

==============================================================================

Sales:

19,20,21,21,22,25,26,30,38

buyer in sale 10(21k) sold for 19k 2 day later, therefore excluding

20 + 21 low outliers

30 + 38 high outliers - https://imgur.com/a/t3Eum4x

buyers at 16.5: https://imgur.com/a/u7e5B1e