Tips for buying a used Mustang Mustang Talk. Buying used What to look for - Ford Mustang Forum. So, you're thinking of purchasing a used Mustang? If this is your first Mustang, I personally commend your plans to enter the world of Mustang. Save $ on a used Ford Mustang. Search over listings to find the best local deals. CarGurus analyzes over 6 million cars daily. Hey all, I have been keeping my eye on new edge GT 5-speed mustangs for a while now. I am still a complete newbie to the mustang. Instead of buying a new car, owners can opt for a used model that provides them excellent value at a lower cost. A used Mustang in particular has the sporty look. Can someone please tell me from his expertise or experience, what millage is acceptable for buying a used mustang /GT from the year range.