Obviously look at the buyers guide on here and also common faults and also ask what petrol gets put in her. anything other than 98 ron, id walk away. buts its up to you.Garage though might not know.
Main thing is make sure the roof works 100%. Engine on, foot on brake, unlatch the clasp then press open, keeping your finger on the button. Try it a few times, after that, try it again. Take it for a run roof down. pull over, put the roof up. Drive back to the garage, put the roof down.
Engine should be running. If its not 100%, motors are 1500 each from Nissan and there are 4 of them. So make sure you are happy. Also any tares in the roof, again 1500 from nissan but I know a guy does them on here for 300 but mixed reviews. Good luck and keep us posted.