Handloading you own will definitely be the cheapest route. Look at plated bullets like campro. Small primered brass will be the cheapest brass available, but you could always look at buying cases in bulk like starline.
Some of the remanufactured ammo out there is more expensive than factory bulk - so buyer beware...
as this is the ammo thread, not the reloading thread, i assumed this was out of op's want. but if he's up for it, cast bullets are even cheaper than plated and you can go even cheaper with casting your own.