Sale 1:

Sold for $37.95 on Marketplace.tf

https://marketplace.tf/items/120;5;u56

https://backpack.tf/item/5037239558

37.95/1.95 = ~19.46

X = 19

Sale 2:

Sold for Neutron Star Nasty Norsemann (Outdated)

http://www.tf2outpost.com/trade/29309429 - B/O of 18

Seller: https://backpack.tf/profiles/76561198089291231#!/compare/1501718400/1501804800

Buyer: https://backpack.tf/profiles/76561198176246931#!/compare/1501804800/1502150400

Buyers at 17+ on the Norsemann:

https://i.imgur.com/cdmy4zT.png

Sale will easily cap.

X = 18 (Capped by B/O)

Sale 3:

Sold for 15 keys

No outpost

Seller: https://backpack.tf/profiles/76561198063640894#!/compare/1505347200/1505520000

Buyer: https://backpack.tf/profiles/76561198201544414#!/compare/1505520000/1505606400

X = 15

Sale 4:

Bulk for Captain Spacemann

Seller: https://backpack.tf/profiles/76561197982305950#!/compare/1506470400/1506556800

Buyer: https://backpack.tf/profiles/76561198114402400#!/compare/1506124800/1506470400

Sales at:

15

18

19

No current sellers.

Going with 15-19.