I guess it depends on how much reloading you're going to do and that's dependent on how much shooting you do. I had an RCBS Rockchucker for a long time-it was one of the older cast iron ones-and it met my needs quite well. I think if I was ever to want to do some more handloading I'd try and get my Rockchucker back from my pal who has it.
You need dies and shell holders as well, and if you use them a lot carbide dies are very nice. You also need a scale and a powder measure, and some brushes to clean out primer pockets. A tumbler to clean and polish your brass is always a nice thing, and these are relatively inexpensive. I used to just clean mine in the dishwasher but that's me.
In addition I had some countersinks that I used to remove the swedge in military primer pockets-I was picking up a lot of military brass out on the desert when I lived in Cali and made a habit of shooting a lot.
There are some nice progressive reloading machines like the ones made by Dillon if you're cranking out a lot of stuff.
Either way a good reloading guide is a great place to start your research into the subject. It's like a lot of stuff-it can be dangerous if you're not careful.
At the store (long since closed) that I got my Ruger Blackhawk at, they had a .41 magnum Blackhawk that had one side of the cylinder blown out and the top strap bulged up about 3/8 of an inch from some improvidently crafted handloads. Likewise one time I was at the range and the guy in the next bay was doing something with a Dan Wesson that was peppering me with lead shavings and I watched him pound the casings out of the cylinder with a dowel and a mallet after every six rounds....not safe at all.