3 of these in existance, 2 are on outpost, one up there has never sold yet, and there have been a handful of sales on the other.

http://www.tf2outpost.com/trade/13220960

Sold with Beams Berliners(~3.9) for Harvest Mountain Cap(~6.4)

6.4 - 4.2 = ~2.5 buds

Proof: http://backpack.tf/id/76561198070143554?time=1375167600 -> http://backpack.tf/id/76561198070143554?time=1375254000

http://www.tf2outpost.com/trade/13082429

cannot find what it sold for

http://www.tf2outpost.com/trade/13051720

Sold with 2 buds + Big Kill for Duped Burning Snaggle(~4.4) - current price is somewhat based on dupes, not 100% sure what he sold his for(stormy KE?)

4.4 - 2.5 = ~1.9 buds

http://www.tf2outpost.com/trade/12877221

Sold with 3 buds + Big Kill for Overclocked El Jefe(no price)

BP After Trade: http://backpack.tf/id/76561198071306074?time=1374735600

Extra Proof here: http://www.tf2outpost.com/trade/13027129

These are all the sales I could find. Seems like he paid quite a lot for that jefe, so I would call that an outlier.