Bubbling: My favorite effect, but not in demand. :^(

Sold for 13 pure: http://backpack.tf/profiles/76561198125906737#!/compare/1467676800/1467849600

Sold for 13 pure: http://backpack.tf/profiles/76561198117597416#!/compare/1467331200/1467417600

Sold for 9 keys pure and roughly 2 keys in sweeties (11 keys): http://backpack.tf/profiles/76561198252999692#!/compare/1465171200/1465257600

Sold for a skullcap dead head (15.5 keys at the time, definite outlier): http://backpack.tf/profiles/76561198079912866#!/compare/1465603200/1465689600 (but capped at 13 anyway: http://www.tf2outpost.com/trade/28246646 so not an outlier?)

Sold for 12 keys, 1 of which was paid in metal: http://backpack.tf/profiles/76561198198564130#!/compare/1467417600/1467504000

Sold for 11 keys pure: http://backpack.tf/profiles/76561198055224435#!/compare/1467504000/1467763200

Rolling with 11-13 because of previously listed sales.

Have yourself a good one. :^)