can a domestic helper get a VOA for zhuhai?

It's possible. As I know, the nationality matters a lot.

Yes, you can apply for one at the border crossing and the price is 130 CNY that should be paid in cashless form. It is advisable to arrive at the border crossing in the earlier morning hours in order to avoid the queues. It is important to understand that Zhuhai VOA is valid for 3 days.