This thing is a nightmare. Only 1 recent valid sale:

Sale 1:

Sold for a gifted bud ~9 keys + 4 keys = 13 keys or 1.3 buds

Before: http://backpack.tf/profiles/76561198117361745?time=1426834800

After: http://backpack.tf/profiles/76561198117361745?time=1427007600

Notes:

Mini for the gifted bud:

http://www.tf2outpost.com/trade/25212399 - offer of 9 keys

Sold for a Stormy Big Elfin Deal + a Sulphurous Cyborg Stunt Helmet + sweets

http://imgur.com/wVkVTl0 - too old to use

Sold for a Vivid Plasma Tyrolean

http://www.tf2outpost.com/trade/24512084 & http://backpack.tf/item/1671163036

It’s unpriced and I can’t find even 1 valid sale (also only 2 exist)

Conclusion:

1 sale at 1.3 buds, thus taking the price at 1.3 buds.