The revised Code of Ethics (US) states that breeders may charge a *refundable* spay/neuter deposit, and veterinary expenses *directly related* to that puppy. Really expenses for the dam wouldn't fall into that category unless it's a singleton litter with one white puppy.
More importantly, though, the COE no longer lists selling a white puppy as an infraction - so those breeders who choose to treat whites as equal to their colored pet littermates are not, technically, in violation of the COE. (It is up to the buyer, of course, to determine whether a breeder actually is charging what they are for whites due to civil disobedience.)
There is a Code of Conduct in the UK, which I believe these days allows white puppies to be sold, but without registration or pedigree. In Canada, white puppies can be sold but must be tattooed or microchipped, and must be on a spay/neuter contract (technically, this surgery is to be done before the pups are sold).