Most people on Medicare are paying $109/month this year. It's $134 for people who enter the system in 2017. You are correct that the higher your income goes, the higher the monthly premium. If you earn more than $85,000, the premium jumps to $187.50.  The maximum is  $428.60 for people earning over $214,000.

https://www.medicare.gov/your-medicare-costs/costs-at-a-glance/costs-at-glance.html#collapse-4809