Seems high, but sales don't lie.

http://www.tf2outpost.com/trade/21390884 Offered + ~0.5 pure (Bills + 5 keys) for Searing Bubble (Outdated at 4, mini at 3.2) + O.Fire Tyrannus (1.5)

No overpay, 4.7 - 0.5 = 4.2

Histories:

http://www.tf2outpost.com/item/440,2813846129,30034,5

http://www.tf2outpost.com/item/440,2756379333,597,5

http://www.tf2outpost.com/item/440,2783932058,151,5

http://backpack.tf/profiles/76561198043114292?time=1406012400

http://www.tf2outpost.com/trade/21375068 Sold for Secret Toque (5.5)

5.5 * 0.9 = 4.95 (rounding to 5)

http://www.tf2outpost.com/item/440,2813846129,30034,5

http://www.tf2outpost.com/item/440,2800309945,97,5

Bubble Mini:

http://www.tf2outpost.com/trade/20878641 Sold for Scorching Counterfeit (3)

3 * 0.9 = 2.7

Histories:

http://www.tf2outpost.com/item/440,1758872073,597,5

http://www.tf2outpost.com/item/440,2756379350,602,5

http://www.tf2outpost.com/trade/20409966 Sold for Aces Brainiac (4.1)

4.1 * 0.9 = 3.69 (rounding to 3.7)

Histories:

http://www.tf2outpost.com/item/440,1758872073,597,5

http://www.tf2outpost.com/item/440,2713353592,590,5

http://www.tf2outpost.com/trade/20375788 Sold for Ghosts Lid (3.1)

3.1 * 0.9 = 2.79 (rounding to 2.8)

Histories;

http://www.tf2outpost.com/item/440,1758872073,597,5

http://www.tf2outpost.com/item/440,2685739875,779,5

Using 2.7-3.7.

Let it ride.