Continuation off of that Orbiting Planets Metal Slug suggestion -> https://backpack.tf/vote/id/56947145dea9e9fc3e597394

1 Year old price. Huh.

Only Valid Sale:

Bp 1: http://backpack.tf/profiles/76561198123231095?time=1447228800&compare=1446624000

Bp 2: http://backpack.tf/profiles/76561198067866620?time=1447228800&compare=1447142400

Sold for an Orbiting Planets Metal Slug.

Price: 13 Keys

Outpost/Classified sellers also support high end drop to 15.

http://www.tf2outpost.com/trade/27630403 < Been selling for 2 weeks @ 15 Keys. Hasn't sold after that period, and reopened a trade for 14.

http://www.tf2outpost.com/trade/27631479 < Has been selling since he received it after the sale with the Planets Slug for 15, poorly bumped but has a backpack listing that's been up for 4 days -> https://backpack.tf/item/1797187135

Thus, going with the range of 13-15 Keys.

Any questions, suggestions, or constructive criticism always welcome. Thanks again for the comments polar.