The cost varies between rescues, but that's about the right amount. You have to bear in mind also neutering (for those old enough), and vet treatment they may need when they come in, the cost of catching/collecting the cat, food etc while the cat is there, and a bit towards the general running of the rescue - near enough everyone working there will be a volunteer. Some rescues will reduce the cost for certain hard to home cats, but that wouldn't be suitable for a first cat for you!
Have you done all the maths of keeping a cat? Many people think they are a very low cost pet, but it's surprising how it mounts up. Insurance (a must!), food, regular vet checks/jabs/worming/flea treatment, food, litter, cat sitter or cattery if you go away... These are all ongoing costs for an animal who can live up to 20.
You need to think about whether you want an indoor only cat or an indoor/outdoor cat. Many cats just aren't suited to an indoor only life though the rescue should be able to advise; then again some cats (usually for health reasons) need to be kept in 24/7. If you intend to let the cat out, are you in a relatively cat safe area (no busy roads) or should you think about getting the garden cat proofed or building a catio? Thinking about these factors and being prepared with your responses can make a difference to the rescue when they consider what cats to show you, or even whether they are prepared to let you have a cat.
A young adult cat is probably a better choice for you for a first cat. Kittens are adorable, but they soon grow up! They can take your house apart, get stuck in impossible places, and you don't really know what they will be like when they grow up. A young adult cat will be past the most destructive stage, and the rescue should have a fair idea what they are like e.g. aloof, cuddly, sedate, high energy etc. Plus many rescues will only re-home kittens in pairs
I wouldn't buy kit or consumables before you decide what you want, and not food, litter etc until you have chosen the cat as, like people, they have likes and dislikes with food & litter - again the rescue can advise on an individual cat. Also if you change food all at once, that can lead to tummy upsets.
A lot to think about, but cats are more than worth it in the end. They have a way of worming themselves into your heart more than you can imagine!