Question about the nissan 350z and autotrader?

im looking to buy a nissan 350z off of autotrader for around 14,000 and with less then 50,000 miles. believe it or not, ive found a few that meets my criteria but i want to know if autotrader is legit? obviously i would test drive the 350z and look at everything, but could i get an inspection some where from a professional? also, i would obviously have to get a loan from the bank one way or the other, and i dont want to pay over 300 dollars a month for the car, so is there anyway i could reach this with the bank? any answers will be greatly appreciated!