Fun fact: These are more rare than the strange Kritzkrieg.

Standard disclaimer as I seem to be the person that makes suggestions on oddity items these days: These are uncommon in the market. Less than 1200 exist; and a large number of them are "special levels" "collector items" or "only as a set." There are higher outlier sales and unbumped trades that are not included.

Currently on classifieds: http://backpack.tf/classifieds/search/id/5201594b4bd7b8cc78000003

1 for 3.6, 3 for 4 keys. Also, Kizuna Austin, if you read this, can you maybe not make a new trade every hour? It makes research difficult.

Selling for under current range

http://www.tf2outpost.com/trade/13806205 3 keys (my wrench I auctioned to him)

http://www.tf2outpost.com/trade/13744765 3 keys

http://www.tf2outpost.com/trade/13544289 3 keys

http://www.tf2outpost.com/trade/13776926 3 keys 1 ref

http://www.tf2outpost.com/trade/13677501 I tried to sell mine for 5 days at 3 keys 2.66 ref. Only got stupid painted offers.

http://www.tf2outpost.com/trade/13764392 3 keys 2.66 ref, says he is "negotiable"

http://www.tf2outpost.com/trade/13782854 3 keys 3 ref (He tried to get 3 keys 5 ref here first http://www.tf2outpost.com/trade/13781157 )

http://www.tf2outpost.com/trade/13016542 3.7 keys

http://www.tf2outpost.com/trade/13791920 3.7 keys

Unsold at 4

http://www.tf2outpost.com/trade/13802408 -Young

http://www.tf2outpost.com/trade/13796944 - Also young

http://www.tf2outpost.com/trade/13793076 1:2 last breath and double cross

http://www.tf2outpost.com/trade/13790650 - 1 day

http://www.tf2outpost.com/trade/13782854 1 day

http://www.tf2outpost.com/trade/13725827 3 days

http://www.tf2outpost.com/trade/13706454 4 days

http://www.tf2outpost.com/trade/13655835 - 6 days

http://www.tf2outpost.com/trade/13617215 1 week

http://www.tf2outpost.com/trade/13295219 2 weeks

http://www.tf2outpost.com/trade/13233388 3 weeks

http://www.tf2outpost.com/trade/12982322 1 month

http://www.tf2outpost.com/trade/12813709 1 month. Still in backpack.

http://www.tf2outpost.com/trade/12971198 1 month. Makes you wonder.

http://www.tf2outpost.com/trade/12520195 Selling since 10 July. Still in backpack.

4 keys does not sell any more; it's time to take it out of the range. These pop up for as little as 3.1 keys, but reliably they go closer to the 3.5 range.