Sale 1:

Sold for 5 keys + 9 ref

Seller: https://backpack.tf/profiles/76561198216670219#!/compare/1521072000/1521158400

Buyer: https://backpack.tf/profiles/76561198180299062#!/compare/1520899200/1521158400

X = 5.5

Sale 2:

Sold for 4 keys + 12.33 ref

Seller: https://backpack.tf/profiles/76561198180299062#!/compare/1522108800/1522195200

Buyer: https://backpack.tf/profiles/76561198146326272#!/compare/1522022400/1522108800

X = 4.5

Sale 3:

Sold for 4 keys + ~19 ref

Seller: https://backpack.tf/profiles/76561198146326272#!/compare/1522108800/1522195200

Buyer: https://backpack.tf/profiles/76561198446606701#!/compare/1522108800/1522195200

X = 4.5

Sale 4:

Sold for 4 keys + ~0.5 keys in ref (some may have been used to buy the strange part)

Seller: https://backpack.tf/profiles/76561198446606701#!/compare/1522454400/1522540800

Buyer: https://backpack.tf/profiles/76561198388363768#!/compare/1522454400/1522540800

X = 4.5

Sale 5:

Sold to a quickbuyer for 4 keys + 6 ref

Seller: https://backpack.tf/profiles/76561198260651783#!/compare/1523318400/1523404800

Buyer: https://backpack.tf/profiles/76561198044335614#!/compare/1523318400/1523404800

X = 4

Sale 6:

Bulk-ish for ’72 RPS

Seller: https://backpack.tf/profiles/76561198094693231#!/compare/1522195200/1522368000

Buyer: https://backpack.tf/profiles/76561198309102410#!/compare/1522022400/1522368000

Bot.tf stats:

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

1 bought at ~4.5 keys

1 bought at ~5 keys

1 sold at 5 keys

X = 4.5

X = 5 (2x)

Sellers:

~4.65 keys:

https://i.imgur.com/8b7cQrZ.png

https://backpack.tf/item/2798231694

~5 keys:

https://i.imgur.com/Ov2MlJA.png

https://backpack.tf/item/2723771293

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

https://backpack.tf/item/2820945601

6 keys:

https://i.imgur.com/qz5UYI2.png

https://backpack.tf/item/4293049258

8 keys:

https://i.imgur.com/fEio9Eq.png

https://backpack.tf/item/5291284780

~10.4 keys:

https://i.imgur.com/5bG8aWf.png

https://backpack.tf/item/3232956536

11 keys:

https://i.imgur.com/LSUPee3.png

https://backpack.tf/item/6009891325

14 keys:

https://i.imgur.com/Vss2bya.png

https://backpack.tf/item/2952072371

https://backpack.tf/item/5340546726

16 keys:

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

https://backpack.tf/item/2781001480

Sales at:

4

4.5 (4x)

5 (2x)

5.5

Sellers at 5 are relatively new, so I’ll keep 5.5 in the range.

4 is too low, excluding 4.

Buyer close to 4.5, but given the amount of sales at ~4.5 keys, it should not be excluded from the range. - just realised the bot's buy orders state that it does not accept cyclone/whirlwind/ssg, which is against the rules. Doesn't not affect this suggestion.

Going with 4.5-5.5.