SELLERS AT ~14 - ~15 KEYS:

http://www.tf2outpost.com/trade/25320682 (14 keys and 14 ref, with name tag and desc)

http://www.tf2outpost.com/trade/25187391 (14 keys and 8 ref)

http://www.tf2outpost.com/trade/25337751 (14 keys, specialized killstreak)

http://www.tf2outpost.com/trade/25002935 (14 keys and 3 ref)

http://www.tf2outpost.com/trade/25242869 (14 keys, killstreak with name tag and desc)

http://www.tf2outpost.com/trade/24787645 (14 keys, with ~2.4 keys worth of strange parts, specialized killstreak, with name tag and desc, but is gifted)

SELLERS AT ~15 KEYS

http://www.tf2outpost.com/trade/25188308 (15 keys, killstreak with name tag and desc and has 7 keys worth of strange parts)

http://www.tf2outpost.com/trade/25156185 (15 keys, killstreak)

http://www.tf2outpost.com/trade/24754678 (15 keys, specialized killstreak, with name tag and desc)

http://www.tf2outpost.com/trade/25284871 (15 keys, specialized killstreak)

backpack.tf sellers are selling for 14 keys: http://backpack.tf/stats/Strange/Festive%20Minigun/Tradable/Craftable

Lowest current market price: $33.35 = ~13-14 keys