MP3 or Peugeot Metropolis used, what to look for, how to insure?

Hello, my question says everything. I want to buy a scooter that I can also drive with a car driver’s license. What I have to pay best attention to when buying a used MP3 or Metropolis. I want to invest something like 4000,- Euro. How to assure this thing best. Price comparison sports have difficulties with the assignment. Thanks Frank