Using last month.

Sale 1:

Sold for $14 on marketplace.tf

https://marketplace.tf/items/1112;5;u3005

Can’t find item’s history.

http://manicbot.me/keyprice/?at=2018-08-14

14/1.88 = ~7.45

X = 7.5

Sale 2:

Sold for 6 keys

Seller: https://backpack.tf/profiles/76561198073973581#!/compare/1531958400/1533254400

Buyer: https://backpack.tf/profiles/76561198063261452#!/compare/1531958400/1532044800

https://backpack.tf/item/2996672039

X = 6

Sale 3:

Sold with 9 ref for 6 keys

Seller: https://backpack.tf/profiles/76561198311498888#!/compare/1533686400/1533772800

Buyer: https://backpack.tf/profiles/76561198336624281#!/compare/1533686400/1533772800

https://backpack.tf/item/6122151377

X = 5.5

Sale 4:

Sold for cheap trash hats and a spelled killer exclusive

Seller: https://backpack.tf/profiles/76561198179948411#!/compare/1533686400/1533945600

Buyer: https://backpack.tf/profiles/76561198362185176#!/compare/1533859200/1533945600

https://backpack.tf/item/4699913485

KE has no recent sales, excluding.

Sellers:

https://i.imgur.com/OvEhNB0.png

10 keys:

https://backpack.tf/item/5156380920

11 keys:

https://backpack.tf/item/3042330277

https://backpack.tf/item/3491758930

https://backpack.tf/item/4502513804

https://backpack.tf/item/3430037928

Sales at:

5.5

6

7.5

Bot.tf states that two have sold within the last month for ~6.5 keys, however, both sales are untraceable.

https://bot.tf/stats/item?def=1112&q=5&ef=Fountain+of+Delight&craft=1&aus=0&ks=0

https://i.imgur.com/3XqWFTQ.png

https://backpack.tf/profiles/76561198312583107#!/compare/1533765600/1533852000

https://backpack.tf/item/3656932532 - buyer’s backpack wasn’t scanned with the item in it

https://backpack.tf/profiles/76561198312583107#!/compare/1533506400/1533592800

https://backpack.tf/profiles/76561198144945119#!/compare/1533340800/1533513600

https://backpack.tf/item/6856735444 - untraceable.

These sales will fall into the range if we manage to trace them.

Going with 5.5-7.5.