Please have a look at the proofs below.

Having a B/O of 1 bud:

http://www.tf2outpost.com/trade/8616361

Having a B/O of 1.33 buds:

http://www.tf2outpost.com/trade/8644551

Current offer for this trade:

http://www.tf2outpost.com/trade/8343412 - 1 bud (after 1 week of posting, no other notable offers)

For the trade with the B/O of 1.33 buds (http://www.tf2outpost.com/trade/8644551), he swapped a direct 1-1 with a massed flies hotrod (average 21 keys).

http://i.imgur.com/ELVu9yQ.png

Conclusion: Prior to the third link receiving an offer of 1 bud while the first link is having a buyout of 1 bud, the higher range can be justified as 28 keys as for now. The lower range is justified with the average price of Massed flies Hotrod which was used in the 1-1 swap for the flies SnS. 21-28 keys would be the suggested price by me.