Resuggestion, Thanks to Xerogyf for the info!

Challenge 19, Team F.L.A.M.B.E.S!

82nd suggestion, made by Beaser!

https://marketplace.tf/items/tf2/247;5;u7

$28.9 / $1.82 = 15.88 keys

$30 / $1.87 = 16.04 keys

https://backpack.tf/item/232076807

https://backpack.tf/item/359663519

Sale #1 -

FoD Rancho (14) + 2 keys = 16

https://backpack.tf/profiles/76561198204215085#!/compare/1590192000/1590451200

https://backpack.tf/profiles/76561199014069450#!/compare/1590451200/1590537600

Rancho Mini:

https://backpack.tf/suggestion/5ef929254799326af83ec03a

Suggestion for 14 keys

Sale #2 -

QS

https://backpack.tf/profiles/76561198151531499#!/compare/1589760000/1589932800

https://backpack.tf/profiles/76561198204215085#!/compare/1589500800/1590192000

Sale 3:

https://backpack.tf/profiles/76561198002757046#!/compare/1587427200/1587513600

https://backpack.tf/profiles/76561198151531499#!/compare/1587427200/1587686400

Sold for 13 keys

Sale 4:

https://backpack.tf/profiles/76561198151531499#!/compare/1589760000/1589932800

https://backpack.tf/profiles/76561198204215085#!/compare/1589500800/1590192000

Sold for 9 keys

Total sales @:

9, 13, 16, 16, 16 keys

considering unsold for 8 motnhs at 15,

https://i.imgur.com/7V9nVHp.jpg

and that 13 resold for lower,

the 16 sales can be considered outliers.

buyers up to 10 keys,

so let's try 13 flat.