Big Wally and I have been having a debate about this. When I was single I discovered that it did in fact cost less for me to eat out than cook at home. Mainly because of the cost of the vegetables! (ok the meats too).  I could actually go to a restaurant and pay less for crab legs than if I bought them at the grocery store and made them myself (I was getting a full meal too). That was a surprise!

There have been a few studies in the last couple of years to point out that, in fact, it may be cheaper to eat out.  Since the details are extensive check out the study here.