This is a very rare Fedora, one of the two remaining unpriced ones, and there are just 2 Stormy 13th ones in existence forever. There have been 2 recent sales on one of them, don't know where the other one is.

http://www.tf2outpost.com/trade/13275346

Sold for this spy set: http://www.tf2outpost.com/trade/13911463

Proof: http://backpack.tf/id/76561198040110511?time=1378450800 -> http://backpack.tf/id/76561198040110511?time=1378537200

The worth of everything besides the charmers is ~1 bud, and the charmers is duped. The seller of the fedora has his B/O on the charmers set at 8.5. Two others of the same dupe on outpost have B/Os of 8.5 and 7 buds, so the normal range of 8.4-8.8 is clearly not acceptable for this duped one. In total I would call this sale about ~8 buds with the charmers at ~7 and the sweets of ~1

The other recent sale on this hat is when Halo bought it, which was sometime around the beginning of august. Backpack history is sparse at best.

http://backpack.tf/id/76561198040110511?time=1373958000 -> http://backpack.tf/id/76561198040110511?time=1375513200

According to this, he bought sometime between the 23rd and 29th (look at the chart). It looks like he bought it for a Roboactive Cosa(~5.9)

Here's the sellers backpack(banned on outpost): http://backpack.tf/id/76561197997252702?time=1375081200 -> http://backpack.tf/id/76561197997252702?time=1375340400

So definitely sold 1:1 with the Roboactive Cosa

However, the owner during the most recent sale had some nice offers that make 5.9 seem like an outlier. These offers include:

-Beams Jeecap(~4.3) + Eerie Jefe(~4.5) = ~8.8 - this is the best visible offer, therefore I will be setting it as the high range

-Harvest Fedora if he adds unknown amount = ~10.5 - ?

-Sulph Nickel Noble - no price, probably at least a 7-8 bud hat

Therefore, price will be 8 - 8.8 on this. Due to there being only 2 in existence forever, and the fact that this is not a new hat or effect, 1 sale should do to set the price for it.