Dealerships tend to overcharge on old used cars, so make sure you don't overpay for a car with 135k miles, generally, I would pay like 3-4 grand for that Infiniti considering the mileage and age. If a mechanic says it's good, it's well maintained, you don't drive the heck out of it like most people do when they buy those Infinitis, you take care of it, go ahead and buy it, they are great fun, and reliable cars. IMO its one of the best cars Infiniti made and they are much better built than the Nissan cars since they are made in Japan. People tend to underestimate Infinitis and call them "endless money pits", but some people just don't maintain them properly and those that do tend to have a long-lasting Infiniti, heck I have seen them with over 500k miles and they still run like a clock.