Proof below.

9 month-old price, needs a slight bump down.

Sales:

http://www.tf2outpost.com/trade/13892351

-wanted ~2 buds

-sold for c9 duty rag=~1.9 buds

http://www.tf2outpost.com/trade/14394596

-wanted ~1.5 buds

-sold for bubbling fez=~1.4 buds

http://www.tf2outpost.com/trade/14142036

-accepted supposed offer of ~1.6 buds

-stahlhelm+hearts pith (1.94 outdated)+2 keys+36 ref (0.38), bought cloudy rubber glove (4.2, outdated price but has b/os around it) here: http://www.tf2outpost.com/trade/13894648

-seller's bp:

http://backpack.tf/id/76561198002728159?time=1379055600 cloudy rubber glove

http://backpack.tf/id/76561198002728159?time=1379228400 hearts pith+stahlhelm+2 keys+36 ref in new items

-~1.9 buds (kind of bulk deal but still fits in range)

http://www.tf2outpost.com/trade/13980618

-b/o of 1.7 buds

-stahlhelm+5 keys, bought vivid robin (outdated) here: http://www.tf2outpost.com/trade/13953812

-~1.4 buds

Current trades (with prices):

http://www.tf2outpost.com/trade/15194160

-b/o of 2.5 buds

http://www.tf2outpost.com/trade/15222143

-b/o of 2.5 buds

http://www.tf2outpost.com/trade/14306273

-b/o of 2.1 buds, more than a month old

http://www.tf2outpost.com/trade/14806426

-b/o of ~1.9 buds

Sales: 1.4, 1.4, 1.9, 1.9

Looking at past and present b/os, I think it's safe to leave 2 buds out of the range. Low end from 2 sales at 1.4, high end from 2 sales at 1.9. Unusual overpay and original prices were used.