Well, someone has to do the dirty fun work.

There are 2 Demonflame Unusual Tartan Spartan to date. The one that is currently in the market was unboxed on 2013/11/01 after a 4 key unboxing -_-

by this user: http://backpack.tf/id/76561198058765525?time=1383289200

The item history is slightly off: http://backpack.tf/item/2035938218

Here is the TF2Outpost Profile of the player, in case anyone wants to know:

http://www.tf2outpost.com/user/77732

After being on the market with no notes: http://www.tf2outpost.com/trade/15475853

The person who unboxed the unusual sold it for an Unusual Modest Metal Pile of Scrap - Miami Nights to this user http://www.tf2outpost.com/user/280311

Current rough valuation on backpack.tf of 7.2-9.5 earbuds.

http://www.tf2outpost.com/trade/15475853 <- the trade where the Demonflame was sold

Flanbius L'enculus sold Demonflame Tartan Spartan for Ghosts Ubersternmann 1:1 http://www.tf2outpost.com/trade/15477887

http://backpack.tf/id/76561197985537786?time=1384588800 2013/11/16

So this is the current owner of the Demonflame Unusual Tartan Spartan:

http://www.tf2outpost.com/backpack/76561198038652715 and he isn't selling it at the moment.

To go on a slight tangent:

The Unusual Das Ubersternmann - Ghosts has had b/o's of 8,12 and 15.

http://www.tf2outpost.com/trade/15808105 Ghosts Ubersternmann trade: looking for 8 pure or 10 unusual overpay

Sold for 1:1 DBD Merrywether http://backpack.tf/id/76561197985537786?time=1384848000 2013/11/19 (date of trade)

festive wow's late trade: http://www.tf2outpost.com/trade/15489462

Looking for a 12 bud b/o or unusual overpay for the Unusual Das Ubersternmann - Ghosts

So either the Tartan Spartan has been undersold, or the incredibly themed, but low effect Unusual Das Ubersternmann has been overpriced.