The whole purpose of pedigreed dogs is to provide a pup that has physical and personality traits that are predictable and to a certain standard. When you cross two breeds with one another you can come up with an awesoome dog, or you could come up with dogs with the bad traits of either parent. Since the parent dogs chosen for this type of breeding are not necessarily being tested and shown for AKC standards, the pups are going to be likely to be backyard breeder products.
When you cross poodles with breeds like retrievers, you are taking two breeds that tend to have ear problems. Their ears are flappy and not enough air gets down in there. Poodles grow alot of hair down inside the canal that needs to be plucked out, but it comes out easily and does not hurt them. Goldens and labs do not generally have hair down in the canal, but goldendoodles and labradoodles do. When you pluck the hair from the ears of these types of dogs it is really painful for them. This occurs even in the Austrailian labradoodle, even nicely bred ones. Believe me, I work for a vet and have to hold down these poor dogs while another person yanks out the hair and the dog cries and yelps.
PLEASE do not breed any of them, anyone. If you have a wonderful crossbreed, great. Love it to death and give it treats after "ear plucking" if it needs it. If it is real lucky it will inherit the golden retriever ears (and just get the typical constant yeast infections). Get used to cleaning dog ears if you are going to own one.
Poodle mixes can be found at the humane society all the time. If they are charging 400.00 it is probably because costs are high in your area. Donate your time or money if you think the situation needs improving.
If you were paying for a pedigreed, show quality poodle or golden retriever and were asked to pay those prices it could be worth it. A dog bred for HEALTH can be a good financial investment. Each breed has its own issues and tests that the parent dogs should undergo to make sure that the new generations are as healthy and great as they can possibly be. This way the breed is improved by their breeding the dogs. For instance, well bred golden retrievers do not have constant ear infections or skin allergies like the typical backyard golden.
Other people should stay the heck out of the business. Extra puppies are not needed in this world, dogs are being euthanized at a shameful rate still in our country.
My advice to you would be to read the ASPCA Guide to Dogs and select a few breeds you like. Then look for a breeder or rescue group in your area that specializes or helps that kind of dog. If you have patience you can find a poodle crossed with another breed you like in rescue and will typically pay alot less and keep one dog from being euthanized in the shelter.
My imput is from the viewpoint of a veterinary clinic worker and dog foster home for dogs from the humane society.