Practicing my high-tier suggestions.

SALES:

http://www.tf2outpost.com/trade/20300579 Sold for 11 pure (10 buds + 20 keys)

Histories;

http://www.tf2outpost.com/item/440,2680179617,135,5

http://backpack.tf/profiles/76561198095437978?time=1402729200

http://backpack.tf/profiles/76561198095437978?time=1402815600

http://www.tf2outpost.com/trade/20125268 Sold + DBD Barnstormer (2.4) + Planets Brigade (Outdated at ~1, mini at 1) (And the brigade's not duped, Twig Mirror bought it BACK (see mini)(Not that it matters)) for Sulph. Bomber (13.8)

OP Comments suggest the Tower was offered, so no overpay, 13.8 - 2.4 - 1 = 10.4 (rounding to 10.5)

Histories:

http://www.tf2outpost.com/item/440,2680179617,135,5

http://www.tf2outpost.com/item/440,2559911039,671,5

http://www.tf2outpost.com/item/440,2669188970,988,5

http://www.tf2outpost.com/item/440,2664369463,105,5

Brigade mini:

http://www.tf2outpost.com/trade/21772418 B/O of 17 keys (2 days)

http://www.tf2outpost.com/user/425252 Sold for Smoking Cosa (~1.3, seller valued it at 1.2 as evidenced by follow-up B/O)

1.2 * 0.9 = 1.08 (rounding to 1.1)

Histories:

http://www.tf2outpost.com/item/440,2829565132,105,5

http://www.tf2outpost.com/item/440,2829565123,459,5

17 keys is near enough 0.9...

Using 0.9 - 1.1

Let it ride.