Cat carrier box - this may be provided by the place where you buy your cat, if not, most good pet stores will have them. The SPCA also supplies pet items including carrier boxes.
Food & Water Bowls - don't be tempted to use your own household items for your pet's bowls; they need their own that can be easily distinguished and kept separate from human eating utensils and crockery.
Food - initially buy small packets or containers of food for your cat until you discover what brand/flavour they prefer. Some cats can be quite finicky so there's no point in buying a large bag of food (that may or may not go to waste) before you've tried a few different options on them.
Brush or comb - this is essential for cats that are especially prone to fur-balls as grooming them helps keep fur-balls out of their digestive tract but also helps keep your furniture hair and fur-free.
Litter & Litter trays - it's absolutely essential that you provide the means for your new cat to be able to go to the toilet in a private, clean place especially when they are not yet accustomed to going outdoors. Ensure you train them use the litter tray so that they are discouraged from using other areas of your home. And place the tray at least 1.5m away from their bedding and food area. Typically, it is difficult to get rid of cat pee once it has seeped into carpet but we provide a number of products that help get rid of the smell and other products that help deter your cat from peeing in areas other than the litter tray.
Scoop for Litter tray - often forgotten this is definitely needed to retrieve the solid litter from the try without having to dispose of the entire bed.
Scratching Post - for some this may seem like a luxury toy, but it is in fact a required item to enable your cat to keep its claws healthy as well as discouraging them from clawing at your furniture. Cats will scratch whether or not you provide a suitable scratching post so it's better that they scratch the post rather than your furniture!
Safety Collar and Bell - collars provide a place for the identification tag and a bell. If your cat goes wandering at least, with a collar, other people will know he or she belongs to someone rather than thinking it potentially being a feral cat. Having an ID tag with a contact phone number on it readily helps you become reunited with your cat. The bell will prove a hinderance to your cat being able to catch and kill birds or bring them into you home as their toy.
Bedding - yes, while cats can sleep anywhere, they also like to have their own bed area that is theirs alone and remains in the same place. Make sure it's in an area that gets shade so they're not sweltering in the sun all day long.
Flea & Worm Treatment - this is a must for keeping your cat healthy and free of fleas or worms. Fleas get worse in the warmer weather and if not treated can spread to your home. Your cat will present with consistent itching and scratching that may result in broken skin or they may be grooming themselves excessively. Cats can get intestinal worms that feed off your cat's food meaning your cat is getting less nutrients from the food resulting in deteriorating health through a distended belly, increased tiredness, and dulling of their coat. Kittens can die as a result of worms if not treated quickly and effectively as their immune systems are still developing and not yet robust enough to counter a severe intestinal worm invasion.