OK, so I'm a skinflint - it's a must when the budget is limited but I like the challenge.
The EasiYo mixes certainly are convenient but also expensive. Granted it's cheaper than buying ready made yoghurt but I remember making yoghurt years ago with heated milk and seeding it with a little bought yoghurt. There's tons of info online and I've been experimenting. So here's what works for me.
Half fill the container with filtered water and add 1½ cups of full cream powdered milk. Put the lid on and shake to mix. Add 2 tab Greek Yoghurt (powder or prepared), fill to the line and replace the lid. Give it a good shake then put it into the prepared thermos. Leave it for about 16 hours and refrigerate. I serve it with strawberry topping or home made strawberry jam. Yum.