Eating Organic for a Week

I have tried all kinds of ways to save money, but I thought I would see how much it really costs for me to eat organic food for a week.  I went shopping today and paid almost 40 dollars for hardly anything.  No one could tell the difference in the taste of the beef tonight, but everyone loves organic chocolate milk!  If the week goes well, I may try it for a month.  It will cost a lot more money, but I think I can cut down costs as time goes on.  Do any of you just eat organic foods?  Are you concerned about GMO products?