You don't need much really.
Wet food is better than dry for health reasons.
Raised bowls are better than floor level. Ceramic is best.
A laser pointer is the best toy. Followed by throwing a small ball into a carrier bag.
I've found the best cat litter tray is quite big with the opening at the top. (Less spillage.)
I think I got our scratching posts from Argos. Just a simple post is fine. One upstairs, one downstairs.
You'll need a good sized carrier. Solid ones give the most protection. Plastic is easy to clean. I line ours with a rubber backed mat (reduces slipping) and an old towel or blanket.
A wet rubber glove can be good for getter hair off furniture. A lint remover is useful too.
If you're buying a collar, get one which can undo easily if caught on something. You'll need a bell too, for the birds. Some cats freak out with a bell but are OK with a kitten bell.
For flea treatment, lots of cats get ill from the chemical treatments. Look into diatomaceous earth which is natural.
For cleaning the floor and litter tray, I use diluted vinegar with a little ecover washing-up liquid.
You'll also need nail clippers and a flea comb.