It is not cheaper than buying the junk cat food. It is cheaper than good quality cat food though. I spend about $10-15 a month for my own cat while with the high end cat food I was spending $20/month. It was a grain free super good cat food though.
Its also much much better for your cat. Spook loves eating raw and has been doing much better on it. His teeth look amazing and he poops a lot less. Also the smell of his poop has changed to a not so nasty smell. On Kibble I could tell he pooped even when I was in a different level of the house, now I never know until I scoop out at the end of the night.
Nightmare ate all canned food - mainly Before Grain. It cost about $45 a month to feed it to him. Now that he is eating raw it is about $12 a month.
I don't know how it compares to feeding dry food, but do know the vet bills will likely end up being much lower if you feed raw. I haven't fed dry for three years so haven't really kept up with anything about it - price or brand wise.
even if the kibble is cheaper, it could very well end up costing more in the long run due to vet bills. it really depends, since there are so many variables involved, but a raw diet could very well be cheaper, esp if you are raising your own animals. there are plenty of resources here to help you learn all about feeding a raw diet that may give you a better idea of how much it will cost, check out the raw food forum here:
For the food itself I did not find raw cheaper than dry foods (and they were "good" dry foods) but I did find it much cheaper than feeding good canned foods. Now we bought all of our meat from our normal grocery store. If you try harder than us and look for free/discount meat on craigslist or scraps from butchers, etc. you can probably do raw much cheaper than we did.
But yeah, it might save you from a few teeth cleanings and other pricy vet visits, so that's something to consider.