Sorry for a delayed reply, I tend not to check the breeding section often.
In my experience for a Zero prices can range from 300-500$ for babies depending on other genetics and overall looks. Adults may run more sometimes as a lot of care has been provided and they are past some of the issues you may run into with a baby.
For a pairing of Zero with a Normal you would end up with offspring that are Het Zero. They would carry the Zero gene, but not show it because they did not receive it from both parents.