While I doubt anyone here is going to be able to find you a reputable "Shih Poo" breeder, as there is no such thing as a reputable designer dog breeder, we can help you find a reputable Shih Tzu or
Here's a link to help you in your search: All AKC-Recognized Breeds Puppies for Sale - AKC Breeders - Puppy Tips Canine Health Information Center: CHIC Breeds
Also, here's the sticky on designer dogs, and why you should reconsider purchasing one. If you are looking for a "hypoallergenic" breed, the Poodle would be great. The truth about designer dogs.
Please read it thoroughly, and educate yourself on why you are interested in either of these breeds (as in, see what behaviors these breeds display, health issues, etc, not just because you like it), and how you can purchase one responsibly. Or rescue one, and save a life.
For the sake of the dogs that are being used for profit by horrible people, and who are dying in shelters every day, don't purchase a designer dog.
Do the responsible thing and save yourself possible a ton of money, future heartache, behavior issues and high vet bills, and get a purebred pup from a reputable breeder or go to a shelter and find a "designer dog" that has been discarded.
I can guarantee you, you can find the perfect best friend for your family without
supporting people like backyard breeders and "designer dog" (mutt) breeders.
You will also be saving the ridiculous amount of money you'd be paying for a mixed breed dog that can be found in shelters, and that money can go towards your new dog's vet appointments, training classes, and just plain spoiling. On top of that, if you go to a shelter or Shih Tzu or Poodle rescue, your dog will already come to you spayed/neutered, with all of it's shots, health and possibly temperament testing.
From a fellow Meghan.