To buy organic or not to buy...

Why is it that anything that is organic costs twice as much as the non-organic stuff? I like to buy organic. I like feeling like it is just a bit better for me than the stuff with all the pesticides and junk. But I have a hard time spending $4.00 for a half gallon of milk when I can pay $3.50 for a full gallon. I just don't get it.