http://www.tf2outpost.com/trade/6265453 -link 1

Offers:-Sunbeams Pyromancer's Mask(~6.3 buds)

-5 buds+white bills~5.4 buds

-Flaming Lantern Salty Dog(~3.5)+Orbiting Fire Surgeon's Stahlhelm(~2.6)~6.1 buds

Sold:~ for Burning Flames Pugilist's(~2.2)+max head(~2)+1 bud lvl 1(~1.1)~5.3 buds-TgM (3 weeks ago)

The best:~6.3 buds,but sold~5.3 buds!?

http://www.tf2outpost.com/trade/6823476 -link 2

Sold:~6 buds-Netsky (1 month ago)

The best:sold~6 buds pure

http://www.tf2outpost.com/trade/7763978 -link 3

Offers:-6 buds pure

-Stormy Storm Modest(~5.6)+ Str. Sapper(11 keys) + S.f Huntsman(16.5 keys)~6.6 buds

The best:~6.6 buds

http://www.tf2outpost.com/trade/6687329- link 4

Offers:-Sunbeams Pyromancer's Mask(~6.3 buds)

-Bubbling Team Captain(~5.8 buds)

- Confetti Team Captain(~5.8 buds)

-Burning Flames Yellow Belt(6.7 buds)

-Sunbeams Fukaamigasa(~5.9 buds)

-Scorching Flames Spartan(~6.5 buds)

The best:~6.7 buds

TOTAL:I found two hats sold(link 1-2), in the price range ~5.3-6 buds(link 1 sold for~5.3,but is offer~6.3)

Max.offer~6.7 buds not pure(link 4)-I'll take the upper price limit,lower price limit-6 buds pure(link 2)