You can try to find a ragamuffin kitten to adopt by searching pet adoption websites such as Petfinder.com, which allows you to search by breed. You can also network with ragamuffin breeders to see if they know of any ragamuffin kittens in need of a home.
Ragamuffin kittens usually don't end up in rescues or shelters, but adults are more common. Stray ragamuffins may not be recognized as such by shelter staff, so it can be helpful to keep an eye on local shelters to see if they get any kittens that look like ragamuffins.
Breeders are more likely to have adult cats available for adoption. These cats may have been sold as kittens and needed to be returned. They are often less expensive than a ragamuffin kitten. Good breeders may be able to help you find a ragamuffin-specific rescue group in your area.
If you choose to buy a ragamuffin kitten, be sure you get it from a responsible breeder who is a member of the Cat Fanciers' Association or other cat breed organization. Breeders should health test their kittens and provide a guarantee of health. Good breeders generally only have one or two litters of kittens each year, and they give their female cats plenty of rest between litters. They should also be interested in your lifestyle and ability to care for the cat, rather than simply handing over kittens to anyone who can pay.