I would like to encourage you to support breeders who respect and love their dogs enough to provide appropriate housing for them.
Sadly, there is a current trend to cut corners in providing a dog appropriate "primary housing" (where the dog spends the majority of the day or night). Instead of kennels, tethers, yards or the freedom of the house, dogs are too often made to live in shipping type crates. This is not only inhumane, but is illegal by not meeting the minimum requirements for USDA regulations for commercial breeders (puppy mills) and animal research facilities!
People who keep their dogs in these conditions will excuse it by saying "dogs are denning animals" which is absolutely false. Dogs, wolves, African hunting dogs - all canids are not "denning animals". Consider the wolf. These animals range MILES each day. The ONLY TIME that a "den" is used is for a few weeks by a female whelping a litter. As soon as the pups can follow, the den is abandoned.
Dogs generally DO ENJOY curling up in a small space, like a crate, to sleep. And using a crate for sleeping can be appropriate, as is using them for travel in cars or airplanes. My objection is to those breeders/owners who use a BOX as a dog's "primary housing". A dog should have sufficient room to move about, drink, and move away from its urine or defecation. Keeping a dog in a box, to take it out to play with and then put it back - this is no way to treat a dog!
Make sure any breeder you are considering does not utilize shipping crates as the primary housing for their dogs.