Quite easy to get for 6 or 6.5 keys, these are swinging from the rafters at 7 keys. I only chose a few links, there are pages unsold at 7. 6.5 does happen occasionally, so that should be the high end.

7 keys

http://www.tf2outpost.com/trade/8158837 - Unsold for 7 keys

http://www.tf2outpost.com/trade/8167623 - Unsold for 7 keys

http://www.tf2outpost.com/trade/7888010 - Unsold for 7 keys

http://www.tf2outpost.com/trade/8224059 - Unsold for 7 keys

http://www.tf2outpost.com/trade/8079178 - Unsold for 7 keys

http://www.tf2outpost.com/trade/8211746 - Unsold for 7 keys

http://www.tf2outpost.com/trade/8154801 - Unsold for 7 keys

http://www.tf2outpost.com/trade/7931147 - Unsold for 7 keys

6.5 keys

http://www.tf2outpost.com/trade/8160663 - Sold for 6.5 keys

http://www.tf2outpost.com/trade/8194572 - Sold for 6.5 keys

http://www.tf2outpost.com/trade/7715045 - Offer of 6.5 keys

http://www.tf2outpost.com/trade/8242163 - Selling for 6.5 keys

http://www.tf2outpost.com/trade/8233736 - Selling for 6.5 keys

6 keys

http://www.tf2outpost.com/trade/8253932 - Selling for 6 keys

http://www.tf2outpost.com/trade/8207183 - Selling for 6 keys

http://www.tf2outpost.com/trade/8219548 - Selling for 6 keys

http://www.tf2outpost.com/trade/8225604 - Selling for 6 keys

http://www.tf2outpost.com/trade/8254740 - Selling for 6 keys

http://www.tf2outpost.com/trade/8206248 - Offer of 6 keys

http://www.tf2outpost.com/trade/7773482 - Offer of 6 keys

http://www.tf2outpost.com/trade/8101445 - Selling for 5 keys

Quite easy to get for less than 7 keys. Comment your thoughts.