I am planning to buy Health Insurance for my Non-US parents. All insurance have Max coverage amount and the cost of insurance increases with the maximum amount. They are going to be here just for 4 months so need advice on how much policy is enough. 50K? 100K? 250K? per person. How much generally are the medical bills. They are 65 and 59 yrs old with few pre existing conditions which any how is not covered.