Just updating the price a little, the last suggestion was based off an old sale.

Rather rare unusual, lots of them in collectors bp for their plague doctor set.

Sold for around 250 USD :

http://i.imgur.com/8wtYSoq.png

Sold to this guy: http://www.tf2outpost.com/trade/18193308

TF2 finance: http://tf2finance.com/ (1 bud = 33 USD)

250 USD/233 = 7.6 buds

Not sure if this will be sufficient for a change, but you can rarely find any on the market for a long time. the only one in the market now wants 12 buds for it.

Low range comes from the last suggestion. Seller had a 7 buds price tag for quite some time: http://www.tf2outpost.com/trade/13469039