This has been the hardest unusual in all 418 unusuals I've owned to sell (besides my duped moon Lucky Shot).

I waited about 2 months, and finally just sold it for an orb fire hard copper plus 3.5 keys in sweets (17 keys with overpay). There are plenty of BO's at 16 keys or lower, though, and it looks like one just sold for 15, so 15 to 17 seems best.

http://www.tf2outpost.com/trade/14966567

Had BO of 15 keys, unsure of what it sold for

http://www.tf2outpost.com/trade/14690732

Two weeks old, BO of 18 and no offers.

http://www.tf2outpost.com/trade/15011554

BO of 17, best offer is like 15 keys pure

http://www.tf2outpost.com/trade/15001839

BO at 19

http://www.tf2outpost.com/trade/14959322

1 week old, semi frequently bumped, BO at 16 keys

http://www.tf2outpost.com/trade/14905184

BO at 17, week old