Trying my best for my first suggestion here, advices on how I can improve my suggestions are appreciated! =)

===Selling/Unsold===

Wants more than 3 keys:

http://www.tf2outpost.com/trade/10202519 (1 month, has S.P.: Robots destroyed, wants 5 keys)

http://www.tf2outpost.com/trade/10781908 (1 week, wants 1:1 for more valuable BK Rocket Launchers)

http://www.tf2outpost.com/trade/10939680 (3 days, has S.P.: Pyros killed, 3.5 keys, unbumped for 2 days)

http://www.tf2outpost.com/trade/10963789 (2 days, wants to trade for more valuable Diamond BK's)

Wants 3 keys:

http://www.tf2outpost.com/trade/10457833 (3 weeks, wants 3 additional crates, offer of Gold BK Medigun Mk.I 2 weeks ago, got 2 adds but stll hasn't sold)

http://www.tf2outpost.com/trade/10522280 (2 weeks)

http://www.tf2outpost.com/trade/10697751 (1 week)

http://www.tf2outpost.com/trade/10825320 (6 days, offer of Strange Your Eternal Reward 6 days ago)

http://www.tf2outpost.com/trade/10933636 (3 days, offer of 3.5 keys in items 3 days ago)

http://www.tf2outpost.com/trade/10946440 (3 days)

http://www.tf2outpost.com/trade/10932218 (3 days, unbumped)

http://www.tf2outpost.com/trade/10969874 (2 days)

http://www.tf2outpost.com/trade/10962983 (2 days)

http://www.tf2outpost.com/trade/11038183 (14 hours)

Wants less than 3 keys:

http://www.tf2outpost.com/trade/10657045 (1 week, 2.5 keys, doesn't have one in his backpack anymore)

Classifieds (http://backpack.tf/classifieds/search/910/11/0):

1 at 3 keys, unbumped for 2 days.

1 with S.P.: Robots destroyed and Dominations for 4.5 keys, valued ~4.68 keys on bp.tf, unbumped for 4 days

===Sold===

http://www.tf2outpost.com/trade/10953417 (2 keys + 2.66)*

I bought 1 for 13.44 ref ( = ~2.6 keys): http://i.imgur.com/fcSdh6L.png)

===Buying/Bought===

http://www.tf2outpost.com/trade/10880595 (2.4 keys, highest offer of buyers)

http://www.tf2outpost.com/trade/6459523 (2.2 keys, got 4 adds for Diamond, "Bought: 9"(Blood, Gold and Diamond in total)

http://www.tf2outpost.com/trade/8220596 (2 keys, got 2 adds)

Othes are just lowballers (want to pay less than 2 keys) or level collectors.

===Offers===

http://www.tf2outpost.com/trade/10914575 (offer of 2 keys + 3 ref, retracted)

http://www.tf2outpost.com/trade/11026176 (offer of 15.33 ref ( = ~3 keys))

Notes:

*The trade is still open (unbumped for 1 day), but the item history shows a different user, so I'm assume he sold it for his stated price.

I know I don't have much proof showing bought/sold for 2.6 keys, but there are only 2 pages of sellers on Outpost which i listed above. I just want to show that people are willing to sell for less than 3 keys. Thanks and have fun!