Second ever suggestion (First one didn't go so well as I had things to learn and the Razor Cut is a bit hard to price because compare is annoying ahhh)

Bought for 13 keys 36 ref rounded to 14 keys.

https://imgur.com/a/raGuR

Sold for a Blizzardy Storm Desert Marauder (17) + 4 keys and a sniper cosmetic = 21 keys

https://backpack.tf/profiles/76561198163191051#!/compare/1517529600/1517616000

Traded for a Misty Skull Handyman's Handle + 3 tickets a munch of ref and 1 key.

[Misty Skull mini (Sold for a DBD Physician's Protector + around 7 in items) (another sold for a Tesla Coil Rebel Rouser priced 26)]

So we have a sale of 35 and a sale of 26 so we will give it a mini of 30.5.

So 30 keys 18 ref and 3 tickets (51 ref) and a key = about 33.

Last sale was sold for 19 keys pure

https://backpack.tf/profiles/76561198212776984#!/compare/1517616000/1517702400

So the sales we have are 14,21,33 and 19