The sale at 9 keys and 14 ref was actually for a whirlwind conga, which has a suggestion at 9-11 right now (might be a bit off but should still fall into the range after correction)

https://backpack.tf/profiles/76561198050726553#!/compare/1537056000/1537142400

https://backpack.tf/suggestion/5ba4812144325a121758f7e0

I don't see 7 keys and 24 ref in your 4th sale, the keys and ref there don't match, so we can exclude that sale. With that in mind, the sale at ~6.5 keys is gonna be too low.

New sale:

$19.99 on marketplace.tf

https://marketplace.tf/items/1120;5;u3003

https://manic.tf/keyprice/?at=2018-10-10 - $19.99 / $1.78 = 11.23 keys

= 11

You'd be better off going with 8-11 with all that in mind

Agreeing with Jarool here, this should be re-sugged at 8-11. Will leave this for a day so you can close yourself.

been a day, closing.