I checked the histories of all 19 Heart Belts, found 3 sales(premium is kool).

6 pure + 2 keys = ~6.1

before: http://backpack.tf/profiles/76561198035688200?time=1416211200

after: http://backpack.tf/profiles/76561198035688200?time=1416297600

8 buds + white bills = ~8.2 (yes the histories of the buds match)

before: http://backpack.tf/profiles/76561197961959293?time=1418630400

after: http://backpack.tf/profiles/76561197961959293?time=1419408000

From the looks of his outpost trade, monky may have paid that much because of the pretty short history(Other clean ones on the market for ~6.2 ( http://www.tf2outpost.com/trade/21662769 ), so I'm calling it an outlier).

It looks like a PE Tyrannus + 3 buds, but the histories don't match :/

http://backpack.tf/profiles/76561198064645544?time=1418976000

http://backpack.tf/profiles/76561198064645544?time=1419062400

As always, suggestions, further proof/counter-proof are always welcome :)