Proof below. 5 month-old price.

Sales:

http://www.tf2outpost.com/trade/15872692

-sold for vivid phantom+6 keys in items=~4.5 buds

http://www.tf2outpost.com/trade/13440502

-wanted 6 buds

-fez+max bought scorching tree (outdated price which is insanely low, the trade was offered 7 buds): http://www.tf2outpost.com/trade/15569095

-using that offer this is 4.6 buds

http://www.tf2outpost.com/trade/14644061

-sold/bought for miami lid: http://www.tf2outpost.com/trade/14740504

-~4.2 buds

http://www.tf2outpost.com/trade/14447850

-old, fez+hearts stovepipe ( http://www.tf2outpost.com/trade/14594858 ) sold/bought for aces war pig (used in suggestion but meh): http://www.tf2outpost.com/trade/14634405

-~4.6 buds

http://www.tf2outpost.com/trade/14790251

-b/o of 5.5 buds on older trade

-sold for 4 buds+2 keys+juju

-buyer's bp:

http://backpack.tf/id/76561198043219650?time=1380351600

http://backpack.tf/id/76561198043219650?time=1381042800

-~4.9 buds

http://www.tf2outpost.com/trade/15916158

-fez+vivid phantom (4.6) sold for burning crown+some sweets: http://www.tf2outpost.com/trade/15942291

-3.6 buds, outlier (4.6 if it wasn't with overpay)

Current trades:

http://www.tf2outpost.com/trade/15298975

-duped, b/o of 6.5 buds

-notable offers:

c9 fez+5 keys=4.2

5 buds

flies fez+planets phantom=5.2

vivid phantom=4.1

phos merry=4.6

beams tree=4.4

http://www.tf2outpost.com/trade/16734728

http://www.tf2outpost.com/trade/16751537

http://www.tf2outpost.com/trade/16750239

-duped, wants 5 buds

http://www.tf2outpost.com/trade/16426488

-wants ~5.6 buds

Sales: 3.6, 4.2, 4.5, 4.6, 4.6, 4.9

Polar suggests a wide range, so 4.2 is from a sale and an offer. 5.2 is from an offer. Overpay and original prices used.