Proof below. 3 month-old price.

Sales:

http://www.tf2outpost.com/trade/16132870

-sold for 42 keys=~2.2 buds

http://www.tf2outpost.com/trade/16017358

-wanted 2 buds

-cosa+stormy fez (1.9) bought terror practitioner (3.1)+nnb l'inspecteur (0.6)+v. luger+random vintages: http://www.tf2outpost.com/trade/16017281

-vintages: http://www.tf2outpost.com/trade/16034506

-~2 buds, no overpay as offered, cannot be higher due to b/o

http://www.tf2outpost.com/trade/15965913

-wanted 2.5 buds

-seems to have bought an amby professional killstreak kit with it: http://www.tf2outpost.com/trade/15981996

-heard these were around 2 buds but not using this

http://www.tf2outpost.com/trade/15876468

-sold for max

-buyer's bp:

http://backpack.tf/id/76561198077406340?time=1385280000

http://backpack.tf/id/76561198077406340?time=1385366400

-~2.3 buds then

http://www.tf2outpost.com/trade/14851841

-b/o of 2.5 buds

-cosa+bills bought strange bubbling bonk boy (outdated but this trade had a b/o of 2.6 buds, lower than price so I'm using that): http://www.tf2outpost.com/trade/14213217

-bills: http://www.tf2outpost.com/trade/14908336

-~2.3 buds, no overpay as offered

http://www.tf2outpost.com/trade/15533839

-bought lantern slouch: http://www.tf2outpost.com/trade/15044658

-2.4 buds but never properly priced so not using

http://www.tf2outpost.com/trade/15348274

-sold for cauldron dixie+0.5 mixed=~2.2 buds

http://www.tf2outpost.com/trade/15306549

-sold for overclocked pugilists (unpriced)+1 bud+7 keys (items)

-surely around 2 buds

http://www.tf2outpost.com/trade/14759344

-wanted 2.5 buds

-bought blizz milkman (he wanted it)=1.9 buds

-milkman: http://www.tf2outpost.com/trade/14700622 (nothing added)

Current trades:

http://www.tf2outpost.com/trade/15574844

-'quickselling' for 2.2-2.3 buds, 1 month

-notable offers:

36 keys=1.9

http://www.tf2outpost.com/trade/4086113

-b/o of 3.5 buds, year old trade

-recent notable offers:

aces shako (unpriced)=around 2 buds?

o.f. company man+2 craft #22s=~1.9 buds

http://www.tf2outpost.com/trade/16156526

-notable offers:

terror bucket=2.3

http://www.tf2outpost.com/trade/15972412

-wants ~2.3 buds, 2 weeks

http://www.tf2outpost.com/trade/15281482

-b/o of 3.5 buds, 1 month

-notable offers:

ge bombing run+1 bud+v. luger=over 3, obvious outlier since he wanted the hat, he could easily have bought another one for ~2

miami bloke (unpriced but definitely ~2)

terror bucket=2.3

http://www.tf2outpost.com/trade/15701168

-up for a month, no good offers

Sales: 1.9, 2, 2.2, 2.2, 2.3, 2.3, 2.4

Low end could either be 1.9 or 2, I choose to go with 1.9 with some offers there and the sale, so no reason to leave it out. For the high end 2.3 is definitely the limit, most b/os are around here. Unusual overpay and original prices used.