Sale 1:

Sold for Green Confetti Frenchman’s Beret (Mini at 16 below) + Strange All-Father (5)

http://www.tf2outpost.com/trade/28418537 - No visible B/O

Seller: http://backpack.tf/profiles/76561198075435735#!/compare/1472774400/1472860800

Buyer: http://backpack.tf/profiles/76561198206556891#!/compare/1472860800/1472947200

X = 21

Sale 2:

Sold for Blizzardy Private Eye (Mini at 19 below) + ~1 key in items

http://www.tf2outpost.com/trade/28567773 - B/O of 21

Seller: http://backpack.tf/profiles/76561198156255538#!/compare/1477699200/1477785600

Buyer: http://backpack.tf/profiles/76561198203587900#!/compare/1477699200/1477785600

X = 20

Sale 3:

Sold with Uncraftable Black Flip-Flops (2.5) for Green Energy Football Helmet (22.5)

No outpost

Seller: http://backpack.tf/profiles/76561198135213739#!/compare/1477440000/1477526400

Buyer: http://backpack.tf/profiles/76561198156255538#!/compare/1477440000/1477526400

X = 20

Sale 4:

Sold for Spec. KS Aussie Minigun (17) in about a day

http://www.tf2outpost.com/trade/28463604 - No B/O

Seller: http://backpack.tf/profiles/76561198040898430#!/compare/1472688000/1472860800

Buyer: http://backpack.tf/profiles/76561198119408257#!/compare/1472774400/1472860800

X = 17

Sale 5:

Bulk for Smoking Dayjogger

Seller: http://backpack.tf/profiles/76561198066649001#!/compare/1477094400/1477180800

Buyer: http://backpack.tf/profiles/76561198135213739#!/compare/1477008000/1477094400

Should be used to update the Dayjogger

Beret Mini:

Only found one proper sale, but that resulted in needing more minis

Seller at 16 for 5 days:

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

http://backpack.tf/u/76561198002757046

Private Eye Mini:

http://backpack.tf/suggestion/5823e294c44045415a6254be

Sellers:

20 keys:

http://i.imgur.com/Jveq8wt.png - listed as 22 here

http://www.tf2outpost.com/trade/28595968 - young

http://backpack.tf/u/76561198124109215

http://www.tf2outpost.com/trade/28538766 - 4 weeks

http://backpack.tf/u/76561197993383111

21 keys:

http://i.imgur.com/ySrSITq.png - 2 months

http://www.tf2outpost.com/trade/28580794

http://backpack.tf/u/76561198076020691

22 keys:

http://www.tf2outpost.com/trade/28591812 - 2 days

http://backpack.tf/u/76561198203587900

Sales at:

17

20 (2x)

21

17 Quicksold, and already looks like an outlier. Excluding 17

Excluding 21 due to the seller at 21 going 2 months unsold, and also because my mini in that sale is crap.

Going with 20 flat