Gladiator.tf:

1st month: https://gladiator.tf/sales?item=Midnight%20Whirlwind%20Taunt:%20Square%20Dance&at=2021-12-26T21:27:12.353Z

Buys:

1 @ 6 keys 22.55 ref ~6.5 keys

1 @ 6 keys 33.77 ref ~6.5 keys

2nd month:

Sales:

1 @ 7 keys

Buys:

1 @ 6 keys 33.22 ref ~6.5 keys

3rd month: https://gladiator.tf/sales?item=Midnight%20Whirlwind%20Taunt:%20Square%20Dance&at=2021-10-26T21:27:12.353Z

Sales:

2 @ 7 keys

Buys:

1 @ 6 keys 4 ref ~6 keys

1 @ 6 keys 31.88 ref ~6.5 keys

~~

https://marketplace.tf/items/tf2/1106;5;u3008

$11.67 / $1.85 = 6.31 keys ~6.5 keys

$11.67 / $1.83 = 6.38 keys ~6.5 keys

~~

https://mannco.store/item/440-midnight-whirlwind-unusual-taunt-square-dance no sales

Sales at 6, 6.5 (x5), 7 (x3)

https://gladiator.tf/listings/61c8923684e615087379b3ab Seller at 6.88 keys (rounds to 7) and seller at 8 keys been there for a year. Buyers at ~6.5 keys

Excluding 6 but keeping 6.5 in the range because it's a common trading point

Going with 6.5-7 keys here