At least I have an excuse for not having this range right the first time.

Unsold for 25 for 10+ days.

http://www.tf2outpost.com/trade/28783006

Sold for a Darkblaze FR-0(29.5 Keys, round to 30)

http://backpack.tf/profiles/76561198075326117#!/compare/1481932800/1482019200

Sold for a Green Energy Larrikin Robin(37 Keys)(Item IDs match)

http://backpack.tf/profiles/76561198260747931#!/compare/1481932800/1482019200

Considering the unsold at 25, this one's safe to call an outlier.

25-30.

Credits to Mindacos + Maximus + Randy for finding the proof, all I did was make the actual suggestion.