I have just discovered Morrisons own cheap brand low fat yoghurt. It actually has less carbs than full fat (dunno how they manage that), has nothing in it but yoghurt, and tastes like it is full fat (but doesnt upset my stomach as full fat can do). AND its only 54p per pot...(500ml) which at a 100ml serving (which I do) is less than 11p per serving 🙂
If you want a pot of yoghurt, low in sugars, try weightwatchers - about same carbs as a full fat yoghurt, but with a bit of flavour added. (And for me, ideal, as very low fat (as opposed to low fat, which can mean anything is added to make up - they dont tell people about the difference!) and I need that for reasons other than weight.)