Read Why Are Kittens So Expensive for a different (but similar) perspective.

The "Price" of adoption

Kittens are priceless.
but they are not free

You should expect to pay between $400 and $700 to adopt a "pet" quality Maine Coon kitten, perhaps more (especially for show quality), possibly less for an older cat.

"But", you say, "that much for a cat? I can get a cat at the SPCA for a $25 donation. I understand there are some purebreds in shelters, they just don't have papers..."

That's true. If that's what you want, go ahead. You may save a life. But if you continue in your quest for a purebred pedigreed Maine Coon, you'll need to start by giving up a common misperception.

You are not buying a cat

That $600 check you write is paying the breeder (a partial payment at that) for many things, including:

time spent understanding what it means to be a Maine Coon
time spent learning the finer points of the breed
buying several cats to show as alters
cat food, kitty litter, toys
scratching posts
vaccinations for the adult cats in the household
costs of attending shows, getting to be known, gaining a good reputation
cat carriers, benching cages, cat trees
learning about breeding
several years of learning what it means to breed cats
learning about genetics and heredity
pedigree research and planning, outcross planning
choosing the sire and dam
cat food, kitty litter, toys
HCM screening, hip screening
buying a breeding female
ensuring that the mother-to-be isn't bred too soon or too often or to the wrong male
setting up a kitten nursery
cleaning and scrubbing with cat-safe products
installing screen doors inside your home, e.g. on the kitty bedroom
installing extra strong screens, screen-porch, etc, for light and air
cat food, kitty litter, toys
vet visits - annual or semi-annual
9 weeks of care for the pregnant female, incl. pre-natal vet visits
assisting mama at delivery time
possible unforeseen circumstances of delivery
12 weeks of care for the kittens
cat food, kitty litter, toys
daily handling and SOCIALIZATION of the kittens
scratching posts
The first three rounds of vaccinations
possibly spay/neuter of the kittens
cat food, kitty litter, toys
interviewing prospective pet parents

I also know of at least two breeders who got a DVM degree so they could better serve their cats.
Do you have any idea what getting a DVM costs?