Proof below. 8 month-old price.

Updated 4 unusuals to price this

Sales:

http://www.tf2outpost.com/trade/18534923

-wanted 5 buds

-dapper+3 keys in sweets bought dp brainiac: http://www.tf2outpost.com/trade/18503199

-~5.6 buds clear outlier, according to polar the recent bump for the brianiac was pretty conservative so the value may actually be lower than this, but I wasn't really able to find much

http://www.tf2outpost.com/trade/18500786

-bought c9 pampered=3 buds

http://www.tf2outpost.com/trade/18250932

-wanted 5 buds

-sold for kaw hwnn set (gold all-father+buccaneer)+bmoc+5 keys

-seller's bp:

http://backpack.tf/profiles/76561198056666854?time=1393660800

http://backpack.tf/profiles/76561198056666854?time=1393747200

-~4.3 buds

http://www.tf2outpost.com/trade/18171334

-wanted 6 buds

-bought phos conq: http://www.tf2outpost.com/trade/18218654

-~2.9 buds also duped

http://www.tf2outpost.com/trade/17865984

-wanted 5 buds

-seems to have sold for stormy bomber (3.75 before overpay)+terror sack (unpriced, likely around 1, look at forum post in proof thread): http://www.tf2outpost.com/trade/18130394

-roughly 4.3 buds

http://www.tf2outpost.com/trade/17830119

-wanted 4.6 buds

-sold for miami dapper+1 bud in sweets=~3 buds

http://www.tf2outpost.com/trade/18395411

-ge dapper (5.05) sold for c9 dapper+big chief: http://www.tf2outpost.com/trade/18768257 + http://www.tf2outpost.com/trade/18768271

-~3.4 buds

http://www.tf2outpost.com/trade/19066986

-sold for planets crone shown from offer in next sale (outdated price): http://www.tf2outpost.com/trade/19030202

-~4.3 buds

http://www.tf2outpost.com/trade/18337184

-wanted 5.5 buds

-sold for shadows sultan (unpriced)+sweets

Current trades:

http://www.tf2outpost.com/trade/19055184

-wants 4 buds

http://www.tf2outpost.com/trade/19136267

http://www.tf2outpost.com/trade/19067571

-wants 5.5 buds

http://www.tf2outpost.com/trade/19113657

http://www.tf2outpost.com/trade/17409890

-wants 5.5 buds, 3 months

http://www.tf2outpost.com/trade/13510548

-up for a millennium, recent offers suck

http://www.tf2outpost.com/trade/18768257

-wants 5.5 buds, 1 month

http://www.tf2outpost.com/trade/19109753

http://www.tf2outpost.com/trade/18992410

-wants 4 buds

Sales: 2.9, 3, 3, 3.4, 4.3, 4.3, 4.3, 5.6

Originally I wanted to go with a narrower 3-4 range based on current trades but given the various sales above 4 near 4.5 maybe this range would be more accurate. Low end of ~3 from sales around there and 4.5 from sales at 4.3 (rounded up).