Hi Star,
Personally, I have a couple of reasons why 'I' wouldn't buy from a breeder. The first one is just that I really have feelings about the cat overpopulation problem and I don't like to encourage people to produce more cats, especially just for companionship purposes, when there's so many great cats who can't find a home. Secondly, spending as much time volunteering at a shelter as I do (a no-kill), I know that there are lots of cats who carry a chunk of genetic material from the breeds and while they don't have papers, they can and do have the look and temperament of any breed you can imagine.
You mentioned health, so I do want to add that it isn't necessarily so that purebreds are guaranteed healthy. There are many problems that can come with inbreeding small groups of cats (and ragdolls are a fairly new breed so there aren't that many with papers and they're closely related) and while people will say they can guarantee health and temperament, there really are no guarantees.
If your heart is really set on a ragdoll cat, I'd encourage you to contact Ragdoll Rescue of America
http://www.petfinder.org/shelters/OR104.html and look at opening your home to a cat that has lost their home. Check it out! They look to have some pretty beautiful cats up for adoption to me :>