Proof below (9 sales). Unusual overpay is applied.

Prices used are of time of sale.

5 month-old price.

1st sale:

http://www.tf2outpost.com/trade/12159284 bought for 3 buds, 2 offers of 3 buds

2nd sale:

http://www.tf2outpost.com/trade/10034487 sold for stormy cosa and 2 buds=3.8 buds (unclear)

3rd sale:

http://www.tf2outpost.com/trade/8918359 added 8 keys to sell for eof cosa=~3.3 buds

4th sale:

http://www.tf2outpost.com/trade/10279681 added 1 key+ to buy bubbling ke=~3.6 buds? (unclear)

5th sale:

http://www.tf2outpost.com/trade/10446546 sold for blizzardy phantom and around estimated 18 keys according to vague backpack history=~3 buds?

6th sale:

http://www.tf2outpost.com/trade/13350118 sold for 3 buds

7th sale:

http://www.tf2outpost.com/trade/13358931 sold for planets bubble pipe and the rest of this set: http://www.tf2outpost.com/trade/13358931 =~3.8 buds

8th sale:

http://www.tf2outpost.com/trade/13355228 along with planets stuntsman (15) and steaming conquistador (21), bought harvest madam dixie (5.1) =~3.4 buds <-not calculating overpay for either sides as I am unable to tell whether it was sold or bought

9th sale:

http://www.tf2outpost.com/trade/13156435 bought blizzardy brainiac hairpiece=~3.8 buds

Notable trades:

http://www.tf2outpost.com/trade/10029021 willing buyer for 4 buds, unable to track exactly what it sold for as it seems too low

Sales: 3, 3, 3, 3.3, 3.4, 3.6, 3.8, 3.8, 3.8

All sales within suggested range, seems about right.