1/1 combination in existence (Well Worn + Hot Effect on Stabbed to Hell Knife). I bought this knife from the person who unboxed it, making it the only sale:

http://imgur.com/0ELuF3V

80 keys + Disco Beatdown Nanobalaclava (24-27 keys).

Unless I price it it will probably never have a value since I'm the only owner.

I am extremely unlikely to ever sell this unless I decide to cash out at some point, so the above sale will be the only one for a long time unless someone else manages to unbox one.

Edit: For those concerned about the Nano price being out of date, here is a sale for 24 pure in February 2016: http://backpack.tf/profiles/76561198056793444#!/compare/1456128000/1456214400