Here's a calculator that might come in handy. It's a real eye opener.
http://www.handloads.com/calc/loadingCosts.asp
You already have free brass that will get re-used after you shoot them up. All you need to worry about is powder (cheap), primers (availability) and bullets (which can be cast later on to save even MORE money).
For example, I can load 9mm lead bullets for $6/50. I'm looking at casting my own from bullet weights, and the cost will drop to about $3.50/50. Current FMJ factory ammo right now locally is $13/50.
But I'm really new at reloading, and I'll say this...don't reload for cost savings. Reload for FUN and so you can shoot more for the same cost. It's like you can make your own gasoline, but find yourself taking that cross country trip instead of down the road to the local park.