Dear lee cel,
You can start from getting yourself and your kids a MediSave-Approved Integrated Shield plan. This insurance will cover most if not all types of hospitalization. You can also choose to top up with as little as 90c a day for a rider that gives your family outpatient benefits such as AnE, TCM etc.
All in all $300/month is sufficient to achieve a comprehensive network of medical benefits for both you and your kids.
Sincerely
Mr Tan