Buy new or near new if you buy a AMG car. Make sure you have a warranty! I have a SL55 AMG and blew the rear struts out on a super hard launch. If the car was not under warranty it would have been thousands out of pocket. The amount you will save by buying a 3 year old car is just not worth it. There is a reason why 3 year old AMG cars out of warranty sell for a lot less than 1 year old cars with a warranty.