It really depends on how much you shoot. I go through about 100 rounds each of .308, .45 ACP and .375 Winchester every time I go to the range, which is about every three weeks or so; a single stage loader therefore works very well for me. It takes me about a day, working pretty slowly, to reload each calibre. If you're shooting every weekend, a bunch more rounds, or you have little spare time, going to a multi-stage loader would be better, but it's also going to cost more initially. On top of the press, there's other parts: dies for priming, expanding, and crimping rounds (usually ~$50 a set, per calibre), sonic bath (wouldn't clean brass without one, can be had at harbor freight for cheap), bullets, primers, and powder all factor into initial and operating costs. You'll also want to set yourself up with a recent book on reloading, as it will give you guidance on how to work up a load for a particular calibre, specs on how much pressure different casings can take when fired, and other important ballistics info.
You'll need to figure out whether you want to cast your own bullets (great for target practice, I'd buy pre-cast for hunting), and it's a good idea to invest in a chronometer...I believe is what it's called. It measures muzzle exit velocity of a projectile, and it's a huge help when balancing bullet weight against the amount of powder in a load.
