Proof below. Unusual overpay is applied.

7 month-old price.

1st sale:

http://www.tf2outpost.com/trade/14175245 sold for 1 bud, seems like a quick sell and outlier

2nd sale

http://www.tf2outpost.com/trade/12105088 old trade, sold for 1.1 buds (24 keys)

3rd sale

http://www.tf2outpost.com/trade/14074633 sold for 1.2 buds (26 keys)

4th sale:

http://www.tf2outpost.com/trade/13211769 sold for 1.3 buds (27 keys)

5th sale:

http://www.tf2outpost.com/trade/12481613 sold for of engineer's cap, doublecross comm and strange original=~1.1 buds (24 keys) at time of sale, as seen here: http://www.tf2outpost.com/trade/12505973

6th sale:

http://www.tf2outpost.com/trade/13278111 sold for 1.2 buds (25 keys)

One on classifieds looking for 30 keys.

Sales: 1, 1.1, 1.1, 1.2, 1.2, 1.3

The 1 bud one seems like an outlier. I'm seeing these go for around 24 to 27 keys, therefore the range.

Edit: Darn, my keys range turned into buds :c Gonna have to change everything to buds