Sellers:

http://www.tf2outpost.com/trade/15644438 5 keys [sold]

http://www.tf2outpost.com/trade/15628217 6 keys [<1 day old] 2 for sale

http://www.tf2outpost.com/trade/15618420 6 keys and 3 ref [1 day old]

http://www.tf2outpost.com/trade/15541692 Strange Sapper and Strange Dead Ringer (~6.5 keys) [4 days old]

http://www.tf2outpost.com/trade/15171554 6 keys and 3 ref [3 weeks old]

http://www.tf2outpost.com/trade/15637123 6 keys and 5 ref [<1 day old]

http://www.tf2outpost.com/trade/15627882 7 keys [<1 day old]

http://www.tf2outpost.com/trade/15641129 7 keys [<1 day old]

http://www.tf2outpost.com/trade/15589172 7 keys [2 days old]

http://www.tf2outpost.com/trade/15568004 7 keys [2 days old]

http://www.tf2outpost.com/trade/15221785 7 keys [2 weeks old]

http://www.tf2outpost.com/trade/15570497 backpack.tf price [2 days old]

http://www.tf2outpost.com/trade/15566314 backpack.tf price [3 days old]

Conclusion: Not enough to include 6 keys, but enough to take 7 keys out.