Litter box, litter (Fresh Step is a good one), food and water bowl, food (Science Diet and Iams are good). That's really all you need. You don't have to buy toys or anything, because cats tend to find their own toys around your house.
Actually, a fun thing to watch them play with is the plastic cap to a water bottle. They love flipping those things around and chasing them all over the room when they roll away. Also, tying a long shoelace to a stick or ruler is good, since you can dangle the lace over the cat's head. They love that.
I don't have a cat anymore, but I grew up owning lots of cats. There's lots of extra stuff you could get the kitty, but it's best to wait until you really get to know the cat. Otherwise, you might end up spending money on extra stuff that the cat isn't even interested in. That's happened to me a couple of times.
BTW, I highly suggest keeping the litter box next to your toilet, so that when you scoop the litter you can just flush the poo. It is so much cleaner that way.
Also, it's fine to leave the cat home while you're at work. The cat will sleep most of the time, and when it's awake and you're not home, it'll just entertain itself.