I don't think it's a waste of money, I think it was actually the best investment in my sanity that I have ever made. But then I had twins (and already a 2 1/2 year old, who's a perfect sleeper) and we lived in the States with no family and no help. It was expensive, but for us it was worth it. I never sleep during the day, just can't, and I couldn't with 3 kids in the house, so getting sleep overnight was important, also for my husband since he works 12 hours a day.
It depends on your situation, and what it's worth for you. I know twins moms who had night help here in HK as well. I didn't need it with my first, but she was an extremely easy child, good sleeper (big baby, not sure that helped) but that doesn't go for everybody. Just see how it goes, how you handle and cope and take it from there. We paid US$25 per hour in the States, we used her from 3-10 weeks old. Then they only woke up once.