Quick updating :

http://backpack.tf/classifieds/search/644/5/31 one in classifieds for 24 keys

http://www.tf2outpost.com/trade/7710389 unsold for 1 bud ~ 27 keys 2 months

best offer 22 keys + ebenezer = 25-26 keys

guy offered bud then quickly retracted

http://www.tf2outpost.com/trade/9099400 24 keys new trade 3 days long

http://www.tf2outpost.com/trade/9128625 1 buds firm price : no any offers ( new trade )

http://www.tf2outpost.com/trade/9137729 1 buds ( new trade )

even all the sellers asking under 29 so 27 seems to be highest value

i'd keep the low end due most of sellers won't go less than it and one offered about 26 too