Proof below. Including trades up to 3 months old due to surprisingly limited proof (none on market) and just to back up the few recent sales.

Sales:

http://www.tf2outpost.com/trade/17792778

-wanted 2.5 buds

-sold for 2.5 buds (overpaid by one key)

http://www.tf2outpost.com/trade/16887465

-3 months old, bought parted sfrl=~2 buds

http://www.tf2outpost.com/trade/17076912

-3 months old, seems to have sold for this pink level 1 max: http://www.tf2outpost.com/trade/17034187

-around 2.1 buds then

http://www.tf2outpost.com/trade/18083665

-was 'quickselling' for ~3 buds

-sold for 50 keys=~2.6 buds

http://www.tf2outpost.com/trade/16994422

-more than 2 months old, wanted 3.5 buds

-sold for c9 marauder=~2.7 buds

http://www.tf2outpost.com/trade/17100796

-3 months old, wanted 6 buds initially

-sold for 41 keys=~2.1 buds according to previous suggestion

Sales: 2, 2.1, 2.1, 2.5, 2.6, 2.7

Including all sales, this gives a range of 2-2.7 and I don't think 2 is too low given a few sales at 2.1.