Pot, mould, sizer are the biggies. There are other small items.
You can go cheap as in Lee, or more spendy for Lyman, RCBS, etc, or some. Mixture of both.
I have a lee bottom pour pot, because it's cheap and it works. I don't particularly care for Lee moulds, so I buy Lyman mostly.
You can buy a lube-sizer for which you will need the proper die and top punch for your bullet, or you can go with a Lee sizing die that bolts on top of a press, and then pan lube. I've never used a Lee sizer.
Depends how much you're going to cast. If you're talking thousands a year, I wouldn't cheap out too much. Though the first upgrade I would myself have, if I were starting out and planned to do some quantity, would be the lube sizer.
That, and buy multi-cavity moulds where possible..
Cabelas and wholesale sports list all of that stuff on their sites. Lee pot is under $100, I think. Lee moulds are 30-ish, and I think their sizer die and a bottle of liquid Alox will set you back another $35 or $40. That's the cheap cheap option. Lyman moulds are $80+, lube sizer is a couple hundred and the dies are about $25 and top punches another $15.