For purposes of this chapter, health insurance is considered reasonable in cost if it is available to the obligor on a group basis or through an employer or union, regardless of service delivery mechanism, or as otherwise defined by the child support agency in compliance with rules promulgated by the secretary of the United States department of health and human services. The definition of reasonable cost established by the child support agency under this section must consider the scope of covered services, the cost of coverage, and the amount of any copayments or deductibles.