Sale 1: 18 keys pure

http://backpack.tf/profiles/76561198049761080#!/compare/1489881600/1489968000

http://backpack.tf/profiles/76561198081806163#!/compare/1489795200/1489968000

Sale 2: Strange Invis Watch (2.3) + Aussie Blutsauger (7) + Spec KS Black Box (13) --> 22.3. --> 22 keys

http://backpack.tf/profiles/76561198012916152#!/compare/1489968000/1490054400

B/O was 22 http://www.tf2outpost.com/trade/28814366 (thanks to Alberny for finding it)

Sale 3: 17 keys pure

http://backpack.tf/profiles/76561198077582798#!/compare/1489622400/1489708800

Sale 4: Sold for Infernal Smoke Taunt: Oblooterated; excluding taunt sale since taunt prices are unstable

http://backpack.tf/profiles/76561198123288580#!/compare/1490832000/1490918400

I count sale 3 as pure since it is mostly australiums and excluded duped sales since we have enough non-dupe sales.

I suggest a range from 17-22