would you buy a G35 coupe has a 200000 Mi on it

Depending on the price, I would have an independent mechanic check it out. Preferably it is from a dealer who at least will give you a mnimum warranty. Buying a car on craigslist is probably a bad idea, unless it is given the thumbs up by a good mechanic.

Generally the G35 is a very well built car and parts which may require replacement on a Nissan vehicle well before 200,000 can last in excess of that. The problem is that not as many Infinitis are sold each year leaving an underwhelming aftermarket for replacement parts. One is forced to buy Infiniti genuine parts from a dealer for alot of items.