Proof below. Overpay calculated

Sales

http://www.tf2outpost.com/trade/13528040 - 18 keys

http://www.tf2outpost.com/trade/13443894 - 17 keys

http://www.tf2outpost.com/trade/12860085 - 15 keys

http://www.tf2outpost.com/trade/14140537 - 17 keys (not 100% sure)

Notable Offers

http://www.tf2outpost.com/trade/14306331 :

- 14.5 keys

- 15 in items (may not actually be worth that much)

- 16 keys + 2 ref + Green Anger = 17 keys

Other trade doesnt have that many notable offers

Conclusion

Never had a price suggestion it seems. >;3 Vote accordingly.

Help / Constructive Criticism / Additional Proof / Counter-Proof is ALWAYS welcome! >;3