Cheapest Unusual

[Iamthest₪rm «Koi»]

So I'm saving up for an unusual, and I want to find legit the cheapest one out there. Cancerous ones. Lowest I've seen is 11 keys, and I've heard one selling for 7. So, can someone help me find the cheapest unusual you can buy? And no, this does not include the Unusual Horseless Headless Horsemann's Headtaker, or Unusual Haunted Metal Scrap.

 

[Iamthest₪rm «Koi»]

Pls vote 4 swag

 

[Iamthest₪rm «Koi»]

Friend linked me this:
http://www.tf2outpost.com/search/189003756