We don't use margarine, but the price of butter here is getting outrageous.
This past week it was on sale for $2.65 lmt 2
So I dug around and found a butter stretcher recipe. It is pretty good and makes the butter spreadable straight from the fridge
1c of butter softened
1/2c of liquid oil (olive, canola ect.)
1/2c of room temperature water
whip the 3 ingredients together till it is a light and fluffy, creamy mixture. Spoon into a container, and use like margarine.
One recipe said that you could leave it out on the counter, but I found that the water sweated out of it. So I keep it in the fridge, and it is soft and spreadable. The whole family likes it.