1 of 2. Only one to have touched the market in a long while.

http://www.tf2outpost.com/trade/25003058

sold for OC warpig(3.35) + 2 buds + 30 keys + 90 ref woth of items( ~ 5.25 key)

Price: 4.8 + (0.9*3.83) = 8.16 ~ 8

http://www.tf2outpost.com/trade/24644847

Sold for 5 buds + blizz berliner's (2.21!)

Seller: http://backpack.tf/profiles/76561198054687092?time=1423209600 = > http://backpack.tf/profiles/76561198054687092?time=1423382400

Price: 0.9*1.75 + 5 = 6.5

Sale #3 - No link

Sold for 8 pure

http://backpack.tf/profiles/76561197995194055?time=1426662000 => http://backpack.tf/profiles/76561197995194055?time=1426748400

This is a bit tricky since the backpack history for the date of trade is not available from the buyer, and the seller has a bunch of stuff to sort through.

However,the buyer has a purple energy eliminator's ( http://backpack.tf/profiles/76561198137120386?time=1426230000 ), which he then sold for 8 buds. Presumably, he used this 8 pure to buy the arcana, as inferred from my chat with the seller, where he stated that "xees bought it for a shit ton of keys" before telling me to fuck off. 8 buds would be about 80 keys on that date, so this seems to corroborate the claim.

Mini for blizz berliner.

http://www.tf2outpost.com/trade/25027338 - 1.5 buds

http://www.tf2outpost.com/trade/25509158 - 17 keys ~ 2 buds

http://www.tf2outpost.com/trade/25492577 - 2 buds

Going with 1.5-2 ~ 1.75