Insurance rates depend on providers and their services. Taking annual insurance will cost you around U$D100 to U$D600 for all services and facilities.
As 'Honda Grom' is used by riders who are students and still in High school or college, luckily, they have extra facilities from the insurance providers. They get a discount of up to 15% on the rate if you can keep up your GPA 3 or above.
Moreover, there are weekly riding courses available. If you take part in those courses,you'll be able to avail more discounts on your annual rate. Apart from this, if you have multiple vehicles and you get them insured from the same company, there are chances that you may get some special discount, which is unofficial.