|beans, weighing scales and ground coffee in the plastic container|
The magic numbers are 60gm of ground coffee and 1 litre of water. So measure the capacity of your cafetiere and do the maths. We learned this at Darkwoods coffee. Please clic on link for a reminder of the January visit this year.
So investment needed: scales, grinder, beans, cafetiere. But if you like your coffee, it's worth it.