Only one has been traded recently.

http://www.tf2outpost.com/trade/10036772 - Offers: Top c/o = 10 in unusuals (9 pure) ; 8.5 Pure

SOLD to 5¹ QP0NDE (Now in the hands of T-Virus, private backpack) http://www.tf2outpost.com/item/440/1526850051

http://backpack.tf/id/76561198053558381?time=1366441200 Atleast 9 buds are tracable from 5¹ QP0NDE, Original amount could have been more since Reese spends his buds piecemeal in the coming days

http://www.tf2outpost.com/trade/9348866 Claims to have sold for 10 pure

http://backpack.tf/id/76561197970657444?time=1363417200

http://backpack.tf/id/76561197970657444?time=1363503600

^ A burning dragon born was sold to buy the killer exclusive so 10 pure is perfectly reasonable