Bonus

Sale 1:

Sold for Power Surge Salty Dog (Suggestion at 49)

No outpost

Seller: https://backpack.tf/profiles/76561198010388715#!/compare/1497830400/1497916800

Buyer: https://backpack.tf/profiles/76561198310610808#!/compare/1497830400/1498003200

X = 49

Sale 2:

Sold for 32 keys the day it became tradable

No outpost

Seller: https://backpack.tf/profiles/76561198080179568#!/compare/1497225600/1497312000

Buyer: https://backpack.tf/profiles/76561198031569942#!/compare/1497225600/1497312000

https://backpack.tf/profiles/76561198080179568#!/compare/1496534400/1496620800 - Bought around 7 days prior to the trade

X = 32

Sale 3:

Sold for Disco Beat Down Whirly Warrior (No mini available) + Orbiting Planets Outta’ Sight

No outpost

Seller: https://backpack.tf/profiles/76561198310610808#!/compare/1498953600/1499212800

Buyer: https://backpack.tf/profiles/76561197999751332#!/compare/1499126400/1499212800

Should support the 49 key sale.

Sale 4:

Bulk for Duped Scorching Milkman

Seller: https://backpack.tf/profiles/76561198266300577#!/compare/1497398400/1497484800

Buyer: https://backpack.tf/profiles/76561198076020691#!/compare/1497398400/1497484800

Sellers:

48 keys:

http://i.imgur.com/lIGGfLa.png - 2 days, lowered from 51:

http://i.imgur.com/5OjfFdq.png - 2 months

https://backpack.tf/item/4083004113

50 keys:

http://i.imgur.com/qzUr8U6.png - 1 month

55 keys:

http://www.tf2outpost.com/trade/29244913 - 1 month

65 keys:

http://www.tf2outpost.com/trade/29227103 - 2 months

74 keys:

http://www.tf2outpost.com/trade/28688408 - 7 months

Sales at:

32

49

32 sold pretty shortly after becoming tradable, and sale 3 would support a higher price. Excluding 32.

Seller at 48.

Going with 48-49.