Again--if there is a question about whether or not a method of euthanasia is painless, don't use it. The entire point is to put the animal out of its misery, not to create more of it.
I won't even dignify the idea that a larger breeder can't afford to have a vet euthanize deformed hatchlings. If they can't afford that, can they also not afford vet care for their normal females? I've heard of this, too. They shouldn't be in business at all if their priorities lie in that direction. If they can't afford to care for all of their animals properly, their animals should be legally seized. That is the way it works when people keep animals but refuse proper care for them.
But the bottom line is that the animals shouldn't be suffering. If you have to euthanize them yourself, then have the decency to hit them over the head with a rubber mallet. Don't freeze them.
At least the rubber mallet definitely isn't cruel, provided you use a proper amount of force. Either method is legally questionable, so you might as well use the painless method. If you don't have the cajones to do that, then take them to the vet.