Finally got it.

Purchased for 43 Keys and a Specialized Market Gardener

-> Market Gardener worth ~ 1-1.2 keys --> http://backpack.tf/stats/Strange/Specialized%20Killstreak%20Market%20Gardener/Tradable/Craftable

http://i.imgur.com/u34RVi8.png?1 (screenshot of the trade)

http://i.imgur.com/zUi5u3v.png?1 (Proof of Market Gardener)

I believe this is the only sale in the last 7 months so one sale should work - the previous owner has had has had it since August, but I managed to weasel it out of him.

I don't plan on reselling, I don't really have any evidence of this other than owning the 1 of 1 vivid stovepipe which I'm keeping too.

First time suggesting so I hope everything's in order! Let me know if I need to change anything :)