Without ammunition, a firearm is not worth much and that ammunition should be reliable. Thus it is wise to acquire and store substantial amounts of ammunition for our weapons.
I reload ammunition for four or five calibers. For a couple of those, it makes sense to do so. For another it is questionable, and for yet another or two, I do it more or less in spite of logic and reason. I decided against reloading for my .40 S&W because I can purchase bulk quantities of .40 caliber practice rounds for only slightly more than I can roll my own – not counting my time. Another reason I chose not to reload for the .40 is reliability – I think factory rounds are less likely to fail. According to my reloading manuals, if a person shoots a .40 S&W in a Glock or other handgun in which the case is not fully supported by the chamber, reloading is a bad idea. Case head failure for the high-pressure .40 can be catastrophic (this does not apply, as far as I know, to the 9mm or the .45). Factory rounds are safer.
Another consideration for reloaders or those thinking about reloading is that components do not store as well as loaded ammunition. This applies mostly to primers, but primers are, in some ways, the most critical element of ammunition reliability. Components have to be stored carefully somewhere that is dry, naturally, without temperature extremes – especially heat. Loaded ammunition, especially factory rounds, is far less susceptible to heat, humidity, and even immersion in water. I’m not saying you can soak your rounds overnight, just that a fall in the creek or getting soaked in the rain isn’t going to cause a problem most of the time. For handloaders, I suggest keeping all available brass loaded. As soon as possible after a shooting session, reload the empties.
For those who shoot ubiquitous standard cartridges like the .223, .30-30, .30-06, .308, .38, .40, or 9mm, reloading is probably not a matter of necessity. However, if a person is a big fan of some “obsolete” caliber such as the .25-35 or the .250 Savage, it is a different story. If the brass for unusual rounds can be found (or in some cases, formed), projectiles, powder, and primers can be easily acquired. Manufacturers producing low-demand cartridges must naturally charge higher prices for those odd rounds than for more common ones. The investment in equipment for reloading the less common ammunition then makes good sense.
For a person who is currently not a handloader, who has no equipment, and who has only firearms in common calibers, I recommend investing what it would cost to buy presses, dies, scales, miscellaneous tools, and components in factory ammo. Online deals are sometimes good, but there is always shipping, and ammunition can be pretty heavy. Some folks do not like buying at Wal-Mart, and I respect that, but I do purchase ammunition there when the prices are right, especially in the case of practice rounds. I also, though, try to support my favorite local gun shop and buy my higher-end, self-defense ammo from there.
I would never want to discourage someone who is interested in handloading from taking up the hobby. It is useful knowledge and a good skill to acquire. If you have the money to invest, by all means do so. I suggest going down to the library and looking for a book on the subject for some initial education. If you have friends or family members who are reloaders, talk to them about it. Check with Midway for books and DVD’s as well as equipment.