For food, the humane society gave me a bag of free food and it made my cat puke a lot. Nothing wrong with it per se, it was decent stuff, but my cat needs grain free food. Pretty sure that's the main thing. Lots of food says grain free right on the bag. I also give her one scoop of wet food every morning. One $2-3 can lasts about 4-5 days. I use Blue Wilderness I think it is called. They have multiple varieties.
Cat carrier, pretty standard, bought one for $50 I think. The soft kind. On a plane it has to fit under the seat in front of you, cats don't travel under the plane I don't think, at least I wouldn't put my cat there. So a hard carrier wouldn't work. Totally a rip off though. It is $100 extra, you have to manually check in at the aiport and it uses up one of your bag allowances for a carry on. I will never do it again unless absolutely necessary.
Litter, I tried some of the flushable and environmentally friendly kinds but both me and my cat hated it. The shredded corn or whatever the hell that stuff was, I found it dusty and didn't cover smells at all. Being able to flush it wasn't worth the hassle of my black cat being covered in beige/brown dust all the time and my entire condo reeking like cat poo.
I eventually settled on old school clay stuff. It is super cheap, albeit a bit of a pain to dispose of because it can't be flushed. But I don't mind. Works great on smell, has very little dust and my cat seems to like it.
Beds, my cat has a cute fluffy igloo that she loves but it is hit and miss. I bought her a cool stand that was on clearance at PetSmart and she only sometimes uses it.
Scratch post, again, test it out. I buy a $15 stand with rope and carpet from WalMart that my cat just loves. But my sister's cat won't use anything similar. Not the cardboard kind, not carpet, not rope.
I use the regular $10 brush from petsmart but I have a few friends that swear by the $50 one called the Eliminator? Something like that. Forget the exact name. It is also sold at petsmart and is super expensive. They say for their long hair cats it works wonders. My short hair doesn't need it that much so I didn't slurge.
Toys, I don't use a laser pointer because my vet said it drives cat crazy because there is nothing tangible and it just pisses them off. I use twist ties, little fluffy mice, bouncy balls and
these and she loves them.