Reloading lets you meddle around and find the most accurate package for your particular rifle. Being able to select a specific bullet for your intended purpose is also an important part of why one reloads.
The cost per shot will be less, although with "just" ammo for the .223 being pretty cheap it's hard to reduce the cost very much.
Overall, there isn't really all that much saving, since most folks just shoot more than if they were buying ready-made retail cartridges. It's a bit different for some of us Old Farts who are using equipment acquired twenty or fifty years ago. Heck, I'm still using .30-'06 dies which were "good used" in 1950...
, Art