Sale 1:

Sold for Flies Baker Boy (Mini at 13 below) + 5 keys

http://www.tf2outpost.com/trade/28664829 - Deleted B/O

Seller: http://backpack.tf/profiles/76561198037674114#!/compare/1482796800/1482883200

Buyer: http://backpack.tf/profiles/76561198110431644#!/compare/1482364800/1483142400

X = 18

Sale 2:

Sold for Steaming Milkman (Mini at 15 below) + 2 keys

http://www.tf2outpost.com/trade/28552218 - B/O of 17

Seller: http://backpack.tf/profiles/76561198021055079#!/compare/1477612800/1477699200

Buyer: http://backpack.tf/profiles/76561198196813762#!/compare/1477612800/1477699200

http://imgur.com/a/UZL2x

X = 17

Sale 3:

Sold for 15 keys

No outpost

Seller: http://backpack.tf/profiles/76561198316193894#!/compare/1477872000/1477958400

Buyer: http://backpack.tf/profiles/76561198273286087#!/compare/1477872000/1477958400

X = 15

Sale 4: (Dupe)

Sold for 14 keys in ~2 days

http://www.tf2outpost.com/trade/28704759 - Deleted B/O

Seller: http://backpack.tf/profiles/76561198077739824#!/compare/1483833600/1483920000

Buyer: http://backpack.tf/profiles/76561198114211310#!/compare/1483920000/1484006400

X = 14

Sale 5:

Bulk for DBD Hong Kong Cone

Seller: http://backpack.tf/profiles/76561198056896965#!/compare/1481932800/1482624000

Buyer: http://backpack.tf/profiles/76561198037674114#!/compare/1482537600/1484352000

Sale 6:

Sold with ~1 key in items for Stormy Tossle Cap

No outpost

Seller: http://backpack.tf/profiles/76561198273286087#!/compare/1478390400/1478476800

Buyer: http://backpack.tf/profiles/76561198157061948#!/compare/1478044800/1479772800

This will be a large outlier.

Flies Baker Boy Mini:

http://backpack.tf/suggestion/587a2a880e2cad0e7d457666

Steaming Milkman Mini:

Sale 1:

Sold for Stormy Liquidator’s Lid (Mini at 17 below)

http://www.tf2outpost.com/trade/28606944 - B/O of 16

Seller: http://backpack.tf/profiles/76561198021055079#!/compare/1479340800/1479427200

Buyer: http://backpack.tf/profiles/76561198186917798#!/compare/1479340800/1479427200

http://imgur.com/a/rORg9

X = 16 (Capped by B/O)

Sale 2:

Sold for 13 keys + 13 ref (>0.5, keys were 24 ref at the time)

No outpost

Seller: http://backpack.tf/profiles/76561198261670113#!/compare/1477526400/1477612800

Buyer: http://backpack.tf/profiles/76561198196813762#!/compare/1477526400/1477612800

X = 14

Going with 14-16 (15) for this.

Stormy Liquidator’s Lid Mini:

Sold on the SCM for $37 USD, (received $32.19) + 1 key + Strange Spec. KS Scattergun (1.5)

http://www.tf2outpost.com/trade/28617474 - B/O of 17

Seller: http://backpack.tf/profiles/76561198021055079#!/compare/1480291200/1480377600

Buyer: http://backpack.tf/profiles/76561198065894983#!/compare/1477785600/1482796800

Chat: http://imgur.com/a/wIl8s

Trade: http://imgur.com/a/PJuNt

Listing: http://i.imgur.com/6SyB9ua.png

Keys were $2.16 at the time

$32.19/2.16 = 14.9

14.9 + 1 + 1.5 > 17

X = 17 (Capped by B/O)

Sellers:

15 keys:

http://i.imgur.com/rHAGKKO.png - 11 days

http://backpack.tf/u/76561198344933095

16 keys:

http://www.tf2outpost.com/trade/28624721 - 1 month

http://backpack.tf/u/76561198043936363

Sales at:

14 (dupe)

15

17

18

Sale at 14 was a dupe, and it sold in only 2 days. Excluding 14.

Going with 15-18