http://backpack.tf/suggestion/588adc62c440450b5b04b507

Original suggestion of the chemistry set for 230 keys (in-date, 2 months plus no other sales will ever occur because that was the only one) Also shows there was 13 already inside it. https://gyazo.com/3b9da37c035b88938febf07fe1bf6b2e

As you can see I crafted it http://backpack.tf/item/5665172154

There were 187 inputs I filled. 187 times 2 refined (price of a brigade helm) is 374 refined. Divide that by 26.55 refined (price of a key) and its 14 keys. So 14 plus 230 is 244 keys. This should be fine.