Yeah, layer feed does cost more, but corn only probably won't give you optimal egg production per lbs of feed they eat. Plus, if you plan on keeping your birds more than 2 years or so, they will likely lose their conditioning much faster than if on a formulated diet. Young birds, much like young animals of any type can survive on less than ideal diets, but their later life will show for it. Doesn't really matter if you have no plans on keeping them around that long though, as they'll probably still lay decently the first year or two. However, if you do plan on keeping them for 4-5 years with the idea they will be decent layers, or for their entire 10+ year life span, you might consider keeping them on pellets as it could be cheaper in the long run. A flock is only as healthy as it's weakest member.