Sale 1:

Sold for 63 keys

No outpost

Seller: https://backpack.tf/profiles/76561198347370367#!/compare/1503705600/1503878400

Buyer: https://backpack.tf/profiles/76561198100072995#!/compare/1503792000/1503878400

X = 63

Sale 2:

Sold for Slumber DCO (Suggestion at 30) + ~18 keys in pure/items

No outpost

Seller: https://backpack.tf/profiles/76561198197287330#!/compare/1508716800/1508803200

Buyer: https://backpack.tf/profiles/76561198148097538#!/compare/1506297600/1508803200

X = 48

Sale 3:

Sold for 47 keys

http://www.tf2outpost.com/trade/29396774 – B/O of 47, seller confirms sale

Seller: https://backpack.tf/profiles/76561198024925599#!/compare/1508025600/1508112000

Buyer: https://backpack.tf/profiles/76561198236206014#!/compare/1508112000/1508889600

X = 47

Sale 4:

Sold in ~2 days for 38 keys

http://www.tf2outpost.com/trade/29390443 - B/O of 39

Seller: https://backpack.tf/profiles/76561198140316312#!/compare/1507334400/1507420800

Buyer: https://backpack.tf/profiles/76561198197287330#!/compare/1507334400/1507420800

X = 38

Sale 5:

Sold for 36 keys

http://www.tf2outpost.com/trade/29370667 - B/O of 38

Seller: https://backpack.tf/profiles/76561198095059670#!/compare/1507248000/1507334400

Buyer: https://backpack.tf/profiles/76561198140316312#!/compare/1507161600/1507248000

X = 36

Sale 6:

Sold for 34 keys + 5 ref to a quickbuyer

Seller: https://backpack.tf/profiles/76561198280729971#!/compare/1505088000/1505174400

Buyer: https://backpack.tf/profiles/76561198024925599#!/compare/1505088000/1505174400

X = 34

Sale 7:

Sold for Slumber Bitey + Duped Blizzardy Phantom

http://www.tf2outpost.com/trade/29352878 - B/O of 56, seller confirms sale

Seller: https://backpack.tf/profiles/76561198024925599#!/compare/1504224000/1504310400

Buyer: https://backpack.tf/profiles/76561198154072948#!/compare/1504310400/1504396800

Should be at least 50 keys.

Slumber DCO:

https://backpack.tf/suggestion/5a09c6f3cf6c753bd54710b7

Sellers:

48 keys:

https://i.imgur.com/uO9LobG.png - 24 days

50 keys:

https://i.imgur.com/jmwET21.png - 2 days

Sales at:

34

36

38

47

48

63

And another sale at around 50-56 (most likely).

Sales at 34, 36 and 38 went to quickbuyers or quicksold. Excluding 34, 36 and 38.

Sales 1 and 7 both occurred more than 2 months ago. Looking at the current sellers, it is clear that the market for this item has changed, and sales more than 2 months old should be excluded, even with the sale at 63 being pure.

Going with 47-48.