This needs a drop.

Classified ads at time of posting:

http://backpack.tf/classifieds/?item=Festive%20Rocket%20Launcher&quality=11&tradable=1&craftable=1

1*17 keys

1*18 keys (Has exorcism)

4*19 keys (1 has killstreak and 2 have parts)

Unsold at 19 keys:

http://www.tf2outpost.com/trade/25660396 (Has killstreak, young)

Sellers at 18 keys:

http://www.tf2outpost.com/trade/25575155 (1 week old)

http://www.tf2outpost.com/trade/25647868 (It's duped, 1 day old)

Seller at 17 keys:

http://www.tf2outpost.com/trade/25629902 (3 days old)

Buyers at 17 keys:

http://www.tf2outpost.com/trade/25500705 (2 weeks old)

http://www.tf2outpost.com/trade/25485010 (2 weeks old)

http://www.tf2outpost.com/trade/25437292 (2 weeks old)

This is all I could find on Outpost that are valid