Re-suggesting with new evidence, hopefully this isn't too messy. Lots of evidence so I'm just compiling everything everyone's contributed:

My original evidence:

https://backpack.tf/profiles/76561198211377312#!/compare/1705449600/1705622400 - seller compare link

https://backpack.tf/profiles/76561198071652927#!/compare/1705449600/1705795200 - buyer compare link

bought for 25 keys

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From Icycrevasse:

MP Sale

https://backpack.tf/item/12652398966

https://marketplace.tf/items/tf2/617;5;u35

$42.99 / $1.70 = ~25 keys (Jan 4)

https://backpack.tf/item/5490204758

https://backpack.tf/profiles/76561198191744974#!/compare/1699401600/1699488000

https://backpack.tf/profiles/76561199183171982#!/compare/1699401600/1699488000

No clue what this sold for

https://backpack.tf/item/754598436

https://backpack.tf/profiles/76561198854496201#!/compare/1699142400/1699401600

https://backpack.tf/profiles/76561199072654974#!/compare/1699228800/1699315200

Dumped for ~16?

https://backpack.tf/profiles/76561199072654974#!/compare/1703203200/1703289600

https://backpack.tf/profiles/76561198144826427#!/compare/1703289600/1704153600

Can't match a complete amt here

Yea 25 flat looks fine here

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From aj:

Might've been a hidden history when you checked this one Icy

https://backpack.tf/item/13080116920

https://backpack.tf/profiles/76561198109506971#!/compare/1706745600/1706918400

https://backpack.tf/profiles/76561199245733895#!/compare/1706659200/1706745600

https://backpack.tf/profiles/76561199245733895#!/compare/1706659200/1706745600

https://backpack.tf/profiles/76561198194626271#!/compare/1706659200/1706745600

https://backpack.tf/profiles/76561198194626271#!/compare/1706659200/1706745600

https://backpack.tf/profiles/76561199245733895#!/compare/1706659200/1706745600

https://backpack.tf/profiles/76561199245733895#!/compare/1706832000/1706918400

https://backpack.tf/profiles/76561198089227368#!/compare/1706832000/1706918400

https://backpack.tf/profiles/76561198089227368#!/compare/1706918400/1707350400

https://backpack.tf/profiles/76561199161916038#!/compare/1706832000/1706918400

https://backpack.tf/profiles/76561199161916038#!/compare/1706832000/1706918400

https://backpack.tf/profiles/76561198208582767#!/compare/1706918400/1706832000

Looks like gamba all the way

https://backpack.tf/item/10305389581

https://backpack.tf/profiles/76561199059800460#!/compare/1703548800/1703635200

https://backpack.tf/profiles/76561198082038479#!/compare/1703548800/1703635200

23 keys match

https://backpack.tf/profiles/76561198082038479#!/compare/1703808000/1703894400

https://backpack.tf/profiles/76561199152294799#!/compare/1708300800/1708300800

21 keys match? Bit odd tbh

Doesn't seem like the full trade

https://backpack.tf/item/5490204758

https://backpack.tf/profiles/76561199183171982#!/compare/1708214400/1708300800

https://backpack.tf/profiles/76561198065879305#!/compare/1708300800/1708387200

Untrace

https://marketplace.tf/items/tf2/617;5;u35 - could be the new MP sale

Feb 20th 2024 - $42.99 / $1.7 = 25.29 keys

3 new sales

1 at 23 keys

1 at 21 keys (?) doesn't make sense and some extra keys come in so it makes me wonder if an item was added as sweets? But also those keys match from a well known gambler so I'm not too sure

1 at 25 keys

https://prnt.sc/KWXrhr1ClE4R

With buyers at 23.69 keys, I think 25 flat is probably fine, maybe 23 - 25 could be argued given buyers have probably risen in the last 2 months since that qs.store December sale for 23 keys

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From aj again:

https://backpack.tf/item/13080116920 - gamba history

https://backpack.tf/profiles/76561198208582767#!/compare/1708905600/1708992000

https://backpack.tf/profiles/76561198208582767#!/compare/1708732800/1708905600

Untrace, probably sold the aussie sticky for keys and then bought the Smoking Ballcap

https://backpack.tf/profiles/76561198152879299#!/compare/1708992000/1712016000

https://backpack.tf/profiles/76561198260467278#!/compare/1708819200/1708992000

Sold to bot

https://backpack.tf/profiles/76561198260467278#!/compare/1711756800/1711843200

https://backpack.tf/profiles/76561197973023301#!/compare/1711756800/1711843200

Sold for:

Purple Confetti Federal Casemaker - https://pastebin.com/6K0KHg84 - sales here

2 keys

https://backpack.tf/profiles/76561197973023301#!/compare/1711843200/1711929600

https://backpack.tf/profiles/76561198095381721#!/compare/1711843200/1711929600

2 keys match

Malevolent Monoculi Airdog - https://backpack.tf/item/12246648375 - this matches history - indate at 15.5 keys

and the 8 keys match

15.5 + 8 = 23.5 keys

Rounds up to 24 keys

https://backpack.tf/profiles/76561198095381721#!/compare/1712102400/1712188800

https://backpack.tf/profiles/76561198136105192#!/compare/1712016000/1712188800

22 keys

https://backpack.tf/item/10305389581

https://backpack.tf/profiles/76561199152294799#!/compare/1710633600/1710806400

https://backpack.tf/profiles/76561199110809353#!/compare/1710547200/1710633600

23 keys to qs.store

https://backpack.tf/item/5490204758

https://backpack.tf/profiles/76561198065879305#!/compare/1710547200/1710633600

https://backpack.tf/profiles/76561199110809353#!/compare/1710547200/1710633600

23 keys to qs.store again

5 new sales

PFetti Casemaker + 2 keys, comes out to 20.5 keys, rounding up to 21 keys

24

22

23

23

One of those 23 key sales was the 25 key MP sale but we also have a new 24 key sale here

I think there is merit to go full range of 21 - 25 keys here or 22 - 25 keys depending on if it's better to range the PFetti casemaker using the Ballcap instead i dunno, will go and annoy price mods

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From Xergoyf:

Only new sale since aj's last comment: https://backpack.tf/profiles/76561198075752272#!/compare/1712448000/1712534400 Sold to bot for ~15.5

Yeah 22 - 25 seems best here, more sales here so better to use the casemaker sale there