Thats hard to really nail down because theres so many variables. Having said that I'll give some general info on the matter and then address specific questions from there.
The break even point really depends on what caliber you are reloading and how much you invested in your reloading setup. I have a good friend who went with a VERY cost effective reloading setup and he has paid for it many times over. He was reloading 270 I think which is fairly expensive. I think he said it was something like 300 rounds to break even, and then he realized savings after that.
Now when you start looking at calibers where there are bulk/mil surp options available it takes a lot longer to break even.
For my reloads on 223/556 the easiest way to explain it is my cost to reload is roughly the same as the cost to buy Wolf ammo. The difference is in the quality. My reloads are a much higher quality ammo for the same price.
Now if you want you can also end up with a slight cost savings as well but to get the full benefit you almost have to buy supplies in bulk. You dont buy enough supplies to reload 50 rounds, you buy enough supplies to reload 5000 rounds.
So without spending half the morning really hunting down the best deals heres an example...
http://www.powdervalleyinc.com/
Ramshot TAC - 8 pounds - $125 (Less $20 hazmat and shipping)
Hornady 55gr FMJ - 1000 - $106
Wolf primers - 1000 - $15
So just so you understand the math theres 7000 grains per pound of powder. As a ballpark lets say you run 25 grains of tac per round.
125/8 = $15.63 per pound.
15.63/7000 = .0022 per grain*25 grains = $.055
Powder = .06
Bullet = .11
Primer = .02
So right there you're at 19 cents per round and thats not counting brass costs, time and equipment. That said that would be a much higher quality round than what you could buy for the same cost. That also doesnt factor in shipping and hazmat either.
You could shave that down a bit by shopping around and buying in larger quantities to get bulk discounts and such but it gives you an idea. I'd say if you REALLY shopped hard you could shave 5, maybe 6 cents a round.
But again, that doesnt account for your time or equipment. If you dropped $400 on your reloading setup and are saving 5 cents a round you have to pull that handle a long time to break even.......
TL;DR
Reloading for mil surp available calibers (9mm, 223) you have to be a very high volume shooter to break even if you desire plinking rounds. If you are looking for benchrest quality ammo the numbers change however but that doesnt seem to be your desired goal.