I haven't made a mini in years. Let me know if I've done it incorrectly.

The sale:

https://backpack.tf/item/9316013082 - one recent sale.

https://backpack.tf/profiles/76561198041108750#!/compare/1602374400/1602547200

https://backpack.tf/profiles/76561198063826027#!/compare/1602460800/1603152000

1:2 for Wicked Wood Universal Translator and White Lightning Brain-Warming Wear.

Mini for Wicked Wood Universal Translator:

Going to use one cash and one pure sale to gauge the price.

Sale 1:

$97.9 mp.tf sale on October 6 - $97.9 / $1.87 = 52.35 keys (https://marketplace.tf/items/tf2/30658;5;u126)

Sale 2:

https://backpack.tf/profiles/76561198163560309#!/compare/1605657600/1605744000

https://backpack.tf/profiles/76561198052766593#!/compare/1603756800/1606003200

Sold for what looks to be 50 keys pure.

50-52 keys range. Valuing the Wicked Wood Universal Translator at 51.

Mini for White Lightning Brain-Warming Wear:

https://backpack.tf/suggestion/5fcc30f78af9b14efe7c5c47

12-13 keys range. Valuing the White Lightning Brain-Warming Wear at 12.5 keys.

Total = 51+12.5=63.5, rounded to 64 keys.

Miscellany:

https://gyazo.com/6a5c10fd243f8ce292c140ffa9e50886

One seller at 100 keys (3 days) and one seller at 150 keys (9 days). This makes 64 look about right.