Last 3 months looked into.

Sale 1:

Sold for 3 keys + 22.11 ref (~3.35 keys)

https://backpack.tf/profiles/76561198890990852#!/compare/1704672000/1704758400

https://backpack.tf/profiles/76561198163665060#!/compare/1704499200/1704758400

https://backpack.tf/item/9916453603

= 3.35 keys

Sale 2:

Sold for ~4 ref in items (~0.05) + Screaming Tiger Disco Fever (Suggestion at 2.4 keys)

https://backpack.tf/profiles/76561199532563131#!/compare/1708214400/1708300800

https://backpack.tf/profiles/76561198297455293#!/compare/1708128000/1708214400

https://backpack.tf/item/2730303653

= 2.45 keys

Sale 3:

Sold for 2 keys

https://backpack.tf/profiles/76561199259453453#!/compare/1708214400/1708300800

https://backpack.tf/profiles/76561198119436383#!/compare/1704153600/1708732800

https://backpack.tf/item/2730303653

= 2 keys

Sale 4:

Sold to a bot for 2 keys + 1 ref

https://backpack.tf/profiles/76561198163665060#!/compare/1704758400/1704844800

https://backpack.tf/profiles/76561199521823568#!/compare/1704758400/1704844800

https://backpack.tf/item/9916453603

This sale follows the purchase at ~3.35 keys.

= 2 keys

Screaming Tiger Disco Fever:

https://backpack.tf/suggestion/65e8191197884edacf0d1151

Other Sales:

#1

https://backpack.tf/profiles/76561198986625008#!/compare/1707609600/1709683200

https://backpack.tf/profiles/76561198111910270#!/compare/1707868800/1708819200

https://backpack.tf/item/14075767874

Untraceable

#2

https://backpack.tf/profiles/76561198890990852#!/compare/1705449600/1705536000

https://backpack.tf/profiles/76561199161916038#!/compare/1705363200/1705449600

https://backpack.tf/item/11735412980

Untraceable. I'm almost certain that it sold for the 2 keys + 22.11 ref we see on the seller's end though.

#3

https://backpack.tf/profiles/76561199201937808#!/compare/1705622400/1705708800

https://backpack.tf/profiles/76561199132627345#!/compare/1705622400/1705708800

https://gladiator.tf/sales?item=%2772%20Taunt:%20Party%20Trick&at=2024-01-21T06:31:27.283Z - labelled as 2 keys + 5.11 ref

https://backpack.tf/item/11735412980

Untraceable

#4

https://backpack.tf/profiles/76561199132627345#!/compare/1705795200/1705881600

https://backpack.tf/profiles/76561199132184792#!/compare/1705881600/1705968000

https://gladiator.tf/sales?item=%2772%20Taunt:%20Party%20Trick&at=2024-01-23T06:31:27.283Z - labelled as 2 keys + 5.11 ref

https://backpack.tf/item/11735412980

Untraceable

#5

https://backpack.tf/profiles/76561199491698756#!/compare/1707782400/1709078400

https://backpack.tf/profiles/76561199059632349#!/compare/1708128000/1708214400

https://backpack.tf/item/5342133860

Untraceable/bulk

#6

https://backpack.tf/profiles/76561199569529898#!/compare/1707091200/1707177600

https://backpack.tf/profiles/76561198258355769#!/compare/1707523200/1707523200 - no prior compare link

https://backpack.tf/item/3637054086

Untraceable

#7

https://backpack.tf/profiles/76561199521823568#!/compare/1705363200/1705449600

https://backpack.tf/profiles/76561198311498888#!/compare/1705363200/1705449600

https://backpack.tf/item/3581060976

Untraceable

#8

https://backpack.tf/profiles/76561199147828410#!/compare/1706054400/1707004800

https://backpack.tf/profiles/76561199496082775#!/compare/1705881600/1707436800

https://backpack.tf/item/2730303653

SCM

#9

https://backpack.tf/profiles/76561199496082775#!/compare/1707436800/1708041600 - backpack won't update

https://backpack.tf/profiles/76561199532563131#!/compare/1708128000/1708214400

https://backpack.tf/item/2730303653

Untraceable

#10

https://backpack.tf/profiles/76561198297455293#!/compare/1708214400/1708300800

https://backpack.tf/profiles/76561198317591798#!/compare/1708128000/1708214400

https://backpack.tf/item/2730303653

Bulk for Blooming Beacon Disco Fever

#11

https://backpack.tf/profiles/76561198317591798#!/compare/1708214400/1708300800

https://backpack.tf/profiles/76561199239151721#!/compare/1687046400/1708300800

https://backpack.tf/item/2730303653

Untraceable, appears to be bulk

#12

https://backpack.tf/profiles/76561199239151721#!/compare/1708300800/1708473600

https://backpack.tf/profiles/76561199259453453#!/compare/1708214400/1708300800

https://backpack.tf/item/2730303653

Untraceable

#13

https://backpack.tf/profiles/76561199499774553#!/compare/1703635200/1709596800

https://backpack.tf/profiles/76561199111073161#!/compare/1706400000/1706486400

https://backpack.tf/item/13562114857

Bulk

#14

https://backpack.tf/profiles/76561199181664199#!/compare/1703980800/1707782400

https://backpack.tf/profiles/76561198280036732#!/compare/1646092800/1708128000

https://backpack.tf/item/10964533870

Untraceable

#15

https://backpack.tf/profiles/76561198311498888#!/compare/1702339200/1702425600

https://backpack.tf/profiles/76561199132184792#!/compare/1702339200/1702425600

https://gladiator.tf/sales?item=%2772%20Taunt:%20Party%20Trick&at=2023-12-13T07:26:47.432Z - labelled as 2 keys + 13.88 ref

https://backpack.tf/item/6776953406

Untraceable

https://backpack.tf/item/10036220468 - marketplace

https://backpack.tf/item/7060851761 - mannco

https://backpack.tf/item/3586496494 - marketplace

https://backpack.tf/item/2984929987 - scammer

https://backpack.tf/item/2777581077 - mannco/marketplace buddies

https://backpack.tf/item/2733060836 - mannco

https://backpack.tf/item/13112643825 - hacked from mannco

Sellers:

https://imgur.com/a/SqOeNrj

https://backpack.tf/item/2964723467 - ~3.15 keys

https://backpack.tf/item/13562114857 - ~3.15 keys

https://backpack.tf/item/2777581077 - marketplace

https://backpack.tf/item/2855336855 - marketplace

https://backpack.tf/item/6258560365 - marketplace

https://backpack.tf/item/2943593917 - marketplace

https://backpack.tf/item/12926783181 - marketplace

https://backpack.tf/item/7179307827 - marketplace

https://backpack.tf/item/5741272452 - marketplace

https://backpack.tf/item/6775605161 - marketplace

https://backpack.tf/item/3586496494 - marketplace

https://backpack.tf/item/6776953406 - marketplace

https://backpack.tf/item/2692131677 - marketplace

https://backpack.tf/item/11735412980 - marketplace

https://backpack.tf/item/2883846015 - marketplace

https://backpack.tf/item/9740999809 - marketplace

https://backpack.tf/item/2764321797 - marketplace

https://backpack.tf/item/10036220468 - marketplace

https://backpack.tf/item/7060851761 - marketplace

https://imgur.com/a/SqOeNrj

https://stntrading.eu/item/tf2/Unusual+%2772+Taunt%3A+Party+Trick

https://backpack.tf/item/3581060976 - 2 keys + 28.22 ref (~2.45 keys)

Sales at:

2 (2x)

2.45

3.35

There is currently 1 buyer for any generic Unusual Party Trick above 2 keys, but given sell listings for other effects below this lone buy order, I would not consider it to be a valid buy order, and will not be excluding 2 from the range.

Seller at ~2.45 keys on STN, and several other sellers for ~3.15 keys on the classifieds. The sale at 3.35 was also a tradeback, so it is invalid anyways. Excluding 3.35.

Taking 2-2.45 keys.