I think both Lee Precision, and Lyman sell starter kits, with the casting pots, etc. to get you started. Check their websites. RCBS may also have something like that.
I prefer a bottom pour casting pot, for casting large caliber balls and bullets. They tend to hold more lead, so you can cast longer before taking a break to add more lead and bring it up to casting temperature. You want a good thermometer, an old spoon you can dedicate solely to casting in order to scrap off the dross that floats to the top. YOu want a good, thick, leather glove, and most want some kind of mallet, or soft headed hammer to use in opening the sprue cutter/ gate.
Some prefer the open top pots, and use a dipper to lift the molten lead out to pour into the molds. If that is for you, get a dipper, too.
Additional equipment that is useful is a good scale to weigh your balls and bullets for uniformity, a Caliper for measuring their diameters, and a lead hardness tester so you can be sure of the lead you put in the pot. After that comes the molds. I have molds made by Lyman, Rapine, Lee Precision, and NEI. There are others. See the Links section here in Member resources at the top of the index page to this forum for names and contact information. Most listed here have on-line catalogues to make it easy for you to shop.