Fisrt, I'd like to point out that there is only 1 of 1 of these hats in existence, and there is only a 5 person history, so finding how much this item was sold for was very tough.

http://backpack.tf/item/3120810091

As you can see, there are really small amount of places I can find this item being sold. You guys can thoroughly check their outpost histories. I've done it 3 times. Only proof:

http://www.tf2outpost.com/trade/24477293 (sold for 4 buds)

Also:

http://www.tf2outpost.com/trade/25363673

(Was offered Molten Mallard Tavish Degroot worth around 4-5 buds. Proof of mallard worth: Was offered:

http://www.tf2outpost.com/trade/24050283

Misty Skull bunsen brave (4-5 buds)

Molten Mallard Bootleg + Blizzard bicorne (25 keys)

Phosphorous bubble pipe + dead presidents yellow belt ( 56 keys)

)

Also, when I added him, I paid my prussian pickelhaube + 2 buds pure. (45 keys total worth)

Also, when comparing the same hats with different effects (eg circling heart and haunted phantasm Jr) Haunted phantasm Jr is overall more expensive

https://backpack.tf/effects/Haunted%20Phantasm%20Jr

http://backpack.tf/effects/Circling%20Heart

Here,

Modest pile of hat (Phas) is 19 buds and (heart) is 12 buds

Master's yellow belt (phas) is 8 buds and (heart) is 6 buds

Cheiftain's challenge (phas) is 4 buds and (heart) is 3 buds

ETC

It can thus be concluded that most haunted phantasm Jr hats are more expensive than the circling hearts, given the amount of hats there are for each effect. (224 for phantasm and a WHOPPING 2761 hats for heart)

http://backpack.tf/unusuals/German%20Gonzila

It can be seen here that circling hearts is 4.25 buds

Hence, if haunted phantasms were to be of higher value than hearts, then it should be priced at 4.3 buds