My very first (unusual) suggestion! Feedback is appreciated!

Unsolds

http://www.tf2outpost.com/trade/28740619 17 keys for 5 month

http://imgur.com/a/1D2hm Seller on tf2 trading forum b/o at 15 keys (not sure if valid pls comment)

Sales 1

https://backpack.tf/profiles/76561198261353286#!/compare/1494633600/1494720000

→ 12 key 10 ref→ rounding to 12.5 keys

Sales 2

https://backpack.tf/profiles/76561198254015856#!/compare/1495152000/1495324800

→ 14 Keys

Sales 3

https://backpack.tf/profiles/76561198254015856#!/compare/1495411200/1495497600

→ 14 keys

Sales 4

https://backpack.tf/profiles/76561198065256484#!/compare/1495497600/1495584000

→ Sold for 2 keys and Miami Crocleather (16.5k indate) → 18.5 keys

Sales 5

https://backpack.tf/profiles/76561198065256484#!/compare/1495411200/1495497600

→ sold for 1 key 5 ref and Blizz storm rubber glove (14k mini below) → round to 15 keys

Sales 6

https://backpack.tf/profiles/76561197981524888#!/compare/1498348800/1498694400

→ 17 keys

Sales 7

https://backpack.tf/profiles/76561198322451572#!/compare/1496880000/1496966400

→ Sold for memory leak voodoo (mini below) → 13.5 keys

Sales 8

https://backpack.tf/profiles/76561198128403236#!/compare/1499212800/1499299200 (was abit confused here cuz sales happened too quickly owner didnt register history of keys)

https://backpack.tf/profiles/76561198337734785#!/compare/1499212800/1499299200 (found it here) → 13 keys 6.88 ref round to → 13 keys

-----------------------------------------

Mini for Blizz rubber: https://backpack.tf/profiles/76561198065256484#!/compare/1495324800/1495411200 (14k)

Mini for voodoo: https://backpack.tf/profiles/76561198150155581#!/compare/1497830400/1498089600 (13.5)

Conclusion: 12.5, 14, 14, 15, 13.5, 13, 17, 18.5 (Outlier cuz unsold at 17k for 5 months)

New Price: 13-15 keys