These 2 Hive Minders have sales you'll need to look into also.

https://backpack.tf/item/5845330310

https://backpack.tf/item/7957644983

Plus, there's an additional sale on Marketplace - https://marketplace.tf/items/tf2/30093;5;u10

28 is buy order price, so that's too low. Additionally, you don't have a data point at 32 Keys, so that cannot be included.

Once the extra sales are looked into, feel free to make another suggestion for this.

If you need help looking through the sales, I'd be glad to help.