Resuggestion after a ton of awesome advice from TF2Scourge. Thanks so much! Big shoutouts to Paradise, Pixxi0us, FishCrimes, and j58 for their help too :)

Ancient Eldritch Smokey Sombrero

Sale 1) Untrace

https://backpack.tf/profiles/76561198106255568#!/compare/1543363200/1545868800

https://backpack.tf/profiles/76561198357047698#!/compare/1545350400/1545955200

Untrace, excluding

Sale 2) Untrace

https://backpack.tf/profiles/76561198357047698#!/compare/1546473600/1546560000

https://backpack.tf/profiles/76561198304735017#!/compare/1546473600/1546560000

Untrace, excluding

Sale 3) Untrace

https://backpack.tf/profiles/76561198304735017#!/compare/1546473600/1546560000

https://backpack.tf/profiles/76561198079040993#!/compare/1546387200/1546560000

Untrace, excluding

Sale 4) 22 Pure - Credit to TF2Scourge for pointing out a mistake I made when finding this sale

https://backpack.tf/profiles/76561198079040993#!/compare/1547856000/1549497600

https://backpack.tf/profiles/76561198168582412#!/compare/1549411200/1549497600

22 Keys

Sale 5) Untrace

https://backpack.tf/profiles/76561198168582412#!/compare/1550102400/1550361600

https://backpack.tf/profiles/76561198262802628#!/compare/1549497600/1550880000

Appears to sell for 20 pure but histories and compare links don’t match up. Excluding.

Sale 6) 12 pure

https://backpack.tf/profiles/76561198400327203#!/compare/1546387200/1546473600

https://backpack.tf/profiles/76561198407285171#!/compare/1546128000/1546387200

Quicksale, Excluding.

Sale 7) Traded w/ 16.33~ ref in sweets for 16 pure

https://backpack.tf/profiles/76561198400327203#!/compare/1546387200/1546473600

https://backpack.tf/profiles/76561198297167809#!/compare/1546387200/1546473600

15.75~ Keys rounding to 16. Countered by Buy Orders. Excluding

Sale 8) Traded w/ G.Fetti Wing Mann(16) + 5 pure for a CTFL Coldsnap Cap

https://backpack.tf/profiles/76561198056793885#!/compare/1546473600/1546560000

https://backpack.tf/profiles/76561198297167809#!/compare/1546473600/1546560000

53 - 21 = 32 keys

Outlier, bulky, & Cap is outdated. Excluding.

Sale 9) Untrace

https://backpack.tf/profiles/76561198209487377#!/compare/1547078400/1547164800

https://backpack.tf/profiles/76561198056793885#!/compare/1547078400/1547164800

Untrace, excluding.

Sale 10) Untrace

https://backpack.tf/profiles/76561198209487377#!/compare/1545091200/1547251200

https://backpack.tf/profiles/76561198112281935#!/compare/1546992000/1547164800

Untrace, excluding.

Sale 11) 22 pure

https://backpack.tf/profiles/76561198112281935#!/compare/1548374400/1548460800

https://backpack.tf/profiles/76561198303138234#!/compare/1548288000/1548547200

22 keys

Sale 12) Bulk for a KaW HKC(50)

https://backpack.tf/profiles/76561198303138234#!/compare/1548633600/1548720000

https://backpack.tf/profiles/76561198156255538#!/compare/1548633600/1548720000

Bulky & lack of minis, excluding

Sale 13) Sold for a Steaming Hallmark(9.5) + 1 key sweets

https://backpack.tf/profiles/76561198846287608#!/compare/1546646400/1546732800

https://backpack.tf/profiles/76561198400562713#!/compare/1546646400/1546732800

Hallmark is outdated and it’s low anyway. Excluding.

Sale 14) 12 pure

https://backpack.tf/profiles/76561198202186637#!/compare/1546819200/1546992000

https://backpack.tf/profiles/76561198803409111#!/compare/1546819200/1546992000

Quicksale, excluding

Sale 15) Untrace

https://backpack.tf/profiles/76561198297577901#!/compare/1546732800/1546819200

https://backpack.tf/profiles/76561198064981372#!/compare/1546473600/1546819200

Untrace or low outlier/quicksale, excluding

Sale 16) Untrace

https://backpack.tf/profiles/76561198064981372#!/compare/1547164800/1547337600

https://backpack.tf/profiles/76561198205629231#!/compare/1547251200/1547337600

Untrace, excluding

Sale 17) Untrace

https://backpack.tf/profiles/76561198205629231#!/compare/1547510400/1547942400

https://backpack.tf/profiles/76561198032448583#!/compare/1547337600/1547769600

Untrace, excluding

Sale 18) Bulk

https://backpack.tf/profiles/76561198032448583#!/compare/1547769600/1547856000

https://backpack.tf/profiles/76561198834678807#!/compare/1547510400/1548028800

Bulk, excluding

Sale 19) Bulk (w/ marked scammer)

https://backpack.tf/profiles/76561198834678807#!/compare/1548028800/1548201600

https://backpack.tf/profiles/76561198262207354#!/compare/1548028800/1548115200

Bulk + marked scammer, excluding

Sale 20) Bulk(?) (w/ marked scammer)

https://backpack.tf/profiles/76561198311498888#!/compare/1548028800/1548201600

https://backpack.tf/profiles/76561198262207354#!/compare/1548028800/1548201600

Marked scammer, excluding

Sale 21) Untrace

https://backpack.tf/profiles/76561198311498888#!/compare/1550102400/1550188800

https://backpack.tf/profiles/76561198311297599#!/compare/1550102400/1550188800

Appears to be part of a bulk trade for a P.Fetti TC & Sunbeams Warhood, but the compare links don’t match. Excluding.

Sale 22) Sold w/ Amaranthine Waxy Wayfinder for Chiroptera Strontium Stove Pipe

https://backpack.tf/profiles/76561198132226518#!/compare/1550102400/1550188800

https://backpack.tf/profiles/76561198311297599#!/compare/1550102400/1550188800

Screenshots of this trade: https://imgur.com/gallery/fnQ3npV - Credit to Pixxi0us, I just uploaded them

Bulky, excluding after advice from FishCrimes

Sale 23) Untrace

https://backpack.tf/profiles/76561198019444465#!/compare/1550016000/1550361600

https://backpack.tf/profiles/76561198132226518#!/compare/1550102400/1550361600

Untrace, excluding

Sale 24) Untrace

https://backpack.tf/profiles/76561198054338720#!/compare/1542067200/1547251200

https://backpack.tf/profiles/76561198335791307#!/compare/1543622400/1543708800

Appears to sell for 24 pure, but the histories and compare links don’t match up. Excluding.

Sales 25 & 26 - Credit to TF2Scourge for pointing these out :)

https://marketplace.tf/items/30682;5;u105

$37.00 / $1.75 = 21.14 keys rounding to 21 keys

36.13/ 1.81 = 19.96 keys rounding to 20 keys

Valid sales: 22, 22, 21, 20

Taking a range of 20-22.

Any advice is much appreciated! Thanks again to everyone that helped me out! :)