there are now a bit more offers and sales, so could be more accurate

http://www.tf2outpost.com/trade/13129524 had an offer of 2 buds

http://www.tf2outpost.com/trade/12387836 sold for planets bicorne (21 keys), seems to be an outlier looking at the other offers

had an offer of nuts beak (1,4) + white bills + 8 keys (2.1 buds)

orb. fire samur-eye (1.3)

http://www.tf2outpost.com/trade/12813445

sold for bud + 20 keys (1.9)

offer of bubling tyrolean (1.5)

http://www.tf2outpost.com/trade/13341795 1.7 bud b/o

someone willing to pay 1.7 pure