For 9mm the greatest savings are realized by casting rather than buying bullets. Years ago when cast bullets were dirt cheap there was little to be saved by doing it yourself. However, today even commercially cast lead bullets are going to cost you almost 10 cents each with tax in even if you don't have to have them shipped. Plated and jacketed bullets raise the price even higher.
Assuming you can get wheel weight lead for $1/pound, 1000 124 gr. 9mm bullets are going to cost you about $18 in materials. Add $70 for a mould and $100 for a Lee 20 pound casting pot and your initial investment is about $200. Once you cast 2000 bullets the mould, pot and WW are paid for. After that you're looking at $18/1000 for bullets vs. $100 or more for commercial. That cost can go down to as low as $0 if you can get the WW cheaper or scrounge range lead for free.
A properly cared for mould will last for 10's of thousands of rounds.
My cost per round has worked out as follows:
brass - free (lots of 9mm brass laying around at the range)
powder - 1.5 cents per round (Bullseye, Titegroup, etc.)
primer - 5 cents each
bullet (range lead powder coated) - free
Cost per round - 6.5 cents or about $3.25/box of 50.
I'm saving at least $11 per box of ammo. Let's say my equipment cost me $220 (mould $70, pot $100, 1 lb. of powder coat $20, size die $30). $220 divided by $11 = 20. So once I've reloaded 20 boxes of ammo (1000 rounds) my entire setup is paid for. After that the only cost involved is primers and powder. Even if you had to occasionally buy cases or wheel weights your average cost should never exceed $5/box. That's a huge savings over commercial ammo and you get to tailor your loads to whatever performance level you want out of them.