Previous price suggestion was six months ago. Since, then, this hat has clearly fallen in demand. Many of them are on the market, and none of them seem to be getting good offers or moving very quickly.

http://www.tf2outpost.com/trade/8184287 - Trader has a 3 bud buyout set. Gets several c/os, all under current price range, which include:

Storms Counterfeit Billycock (1.3 - 1.6 buds) + Crate 40 (6-8 keys) + un-named sweeteners

Smoking Berliner's (24 - 29 keys)

Sunbeams Hetman's (1.7 - 2.2 buds, average of around 2 buds) plus six keys

Only one of those offers falls in the current price range, and 90% of that offer is in unusuals, not promos or cash.

http://www.tf2outpost.com/trade/8421598

Same trader gets a couple of offers, all far under 2 buds.

http://www.tf2outpost.com/trade/8147885

Trader claims to have several cash offers of around $100, but does not explain where they are from. Was also offered a Beams Mongolian (1.4 - 1.8 buds) + 3 keys, a Searing Plasma Private Eye (1.8 - 2.3 buds) and an S.F. Axtinguisher (5-6 keys) for it. All offers except the unsubstantiated cash ones are below current price range in pure.

Of the eight of these hats that exist, four appear to be on the market at this time.

They've become less valuable because people who have them are trying to trade them, and people who are offering are not offering the price listed in the previous range. Rarity =/= value. The Cave promos, for instance, are THE rarest genuines in the game - but they're all worth a key or less each.