I thought Mexican Monkey would have reposted this, but ... here it is. His evidence mixed in with mine, 2.4 - 2.5 keys should be an okay range for now.

http://www.tf2outpost.com/trade/7950069 - Offered 2 keys + 3 ref

http://www.tf2outpost.com/trade/10456786 - Offered 2 keys + 2.44 ref

http://www.tf2outpost.com/trade/10604615 2 keys 1 ref each (when buying 5+)

http://www.tf2outpost.com/trade/10597620 2.4 keys

http://www.tf2outpost.com/trade/10411491 2.4 keys

http://www.tf2outpost.com/trade/10612910 2.4 keys

http://www.tf2outpost.com/trade/10491999 buy trade at 2.2

http://www.tf2outpost.com/trade/10530932 2.4 keys

http://www.tf2outpost.com/trade/10128864 2.44~ keys

http://www.tf2outpost.com/trade/10613089 2.2 keys (new trade)

http://www.tf2outpost.com/trade/10494919 2.4 keys (same guy as the buy trade at 2.2)

http://www.tf2outpost.com/trade/10532553 my trade - 2.4 keys 2 days old.

http://www.tf2outpost.com/trade/10604147 2.4 keys (no autobump)

http://www.tf2outpost.com/trade/10585774 2.4 keys (no autobump)

http://tf2tp.com/trade.php?trade=9412021 - Sold 2 keys + 3 ref

http://tf2tp.com/trade.php?trade=9411453 - Sold 2 keys + 2.44 ref (can be considered 1/2 of key)

http://tf2tp.com/trade.php?trade=9405655 - Sold 2 keys + 3 ref

http://tf2tp.com/trade.php?trade=9401498 - Sold 4 at 2.5 keys.