I am a mom of twins, and I used Parent's Choice formula. It was much less expensive, and when you get to feed twins.. you KNOW that adds up like crazy!
Parent's Choice has a savings calculator on their site for anyone who's thinking about switching formulas to save money. http://www.parentschoiceformula.com/baby-formula-savings-calculator.aspx It's amazing how much you save with store brand formulas and without sacrificing baby's nutrition!
I was lucky that I didn't have any special circumstances for my girls, so we were able to use store brand just about anything.. and the best value for our money we were able to find in Parent's Choice brand items, diapers, wipes, etc. They even have foods! I love saving money!!!